JP2000141081A - Solid wire for gas shielded arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable obtaining appropriate strength and sufficient low temperature toughness as 400-520 N/mm2 class and at the same time preventing salt damaging corrosion, and to make it possible to obtain weather resisting performance not less than weather resisting steel of conventional naked specification in a non salt damaging corrosion environment. SOLUTION: The solder wire contains, by weight, 0.02-0.10% C, 0.30-1.00% Si, 1.20-2.00% Mn, 0.40-0.60% Cu, 1,40-2.30% Ni, 0.15-0.30% Ti, <=0.15% Mo, and the balance Fe with inevitable impurities, and is regulated to be, by weight, <=0.015% P, <=0.020% S, <=0.15% Cr, <=0.030% Al, <=0.010% Nb, 0.010% V, <=0.010% N, and <=0.040% total amount of Al, Nb, V and N; when each of the content of Cu, Ni and Ti is respectively indicated by [Cu], [Ni] and [Ti], the value of parameter A, expressed by A=0.3×[Cul]+0.5×[Ni]+[Ti], is 1.00-1.45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire for gas-shielded arc welding, and more particularly to a gas-shielded arc welding wire having excellent corrosion resistance in both a salt corrosion environment at a beach and a non-salt corrosion environment at a mountain. Regarding wires.

[0002]

2. Description of the Related Art As is well known, JI is used as a weather-resistant steel sheet.
Specified in SG 3114. This weather-resistant steel plate has a property that rust forms a stable and dense state even in an exposed state and serves as a protective film, thereby preventing the progress of corrosion. Also, appropriate amounts of Cu and C as chemical components
The addition of r is a feature of the weather-resistant steel sheet, and an appropriate amount of Ni may be added. The solid wire for welding applied to this steel sheet is JIS
There is a "solid wire for carbon dioxide arc welding for weathering steel" specified in Z3315. In order to obtain the same corrosion resistance as the weather-resistant steel sheet, an appropriate amount of C
u and Cr are added. Further, an appropriate amount of Ni may be added.

[0003] However, these conventional weather-resistant steel sheets or weather-resistant welding wires are effective in an inland environment where chlorine does not fly, but are less effective in an environment where chlorine adheres to a beach area. I understand that. This is thought to be because chlorine ions adhering to the steel sheet surface lower the pH of the stable rust film, form a hydrochloric acid atmosphere at the interface between the rust film and the steel, and promote the corrosion of the steel.

[0004] Steel containing Cr, together with chlorine ions,
Since the Cr ions have the effect of lowering the pH of the stable rust film, the conventional weather-resistant steel or weather-resistant welding wire has insufficient salt damage corrosion resistance.

[0005] Therefore, as a weather-resistant steel having excellent resistance to salt damage and corrosion, a component system containing no Cr has been considered. The same applies to welding wires.
No. 82 discloses a wire for fire-resistant steel which does not contain Cr, prevents corrosion when used in a beach, and has excellent weather resistance.

[0006]

However, Japanese Patent Laid-Open Publication No.
In the wire disclosed in Japanese Patent No. 00582, regarding the weather resistance, only Cr was not added, but Cu and Ni were added.
Is almost the same as the range of JIS Z 3315, and no other means for improving corrosion resistance is taken. Therefore,
Although the salt damage resistance is improved, the normal weather resistance (non-salt damage corrosion environment) has a problem that stable rust is insufficient due to no addition of Cr, and the corrosion resistance is lowered.

[0007] The wire disclosed in Japanese Patent Application Laid-Open No. 5-200582 contains Mo or V for the purpose of enhancing high-temperature strength in order to provide fire resistance. Adversely affect. For refractory steel,
Almost all of them are used for building such as buildings, but most of weather-resistant steel is used for bridges and the like. Bridges are important structures and require low-temperature toughness of less than 0 ° C as required mechanical performance. In particular, in recent years, in most cases, a toughness of -10 to -30 ° C is required as a specification for cold regions. Therefore, there is a welding wire that has sufficient low-temperature toughness for weathering steel, prevents salt damage corrosion, and in a non-salt damage environment, provides weathering performance equal to or better than conventional bare specification weather resistance. There is a problem that did not.

The present invention has been made in view of the above problems, and has a proper strength and sufficient low-temperature toughness of 400 to 520 N / mm ² class, and can prevent salt damage corrosion. It is an object of the present invention to provide a gas shielded arc welding solid wire capable of obtaining a weathering performance equal to or higher than that of a conventional bare specification weathering steel in a non-salt damage corrosion environment.

[0009]

The solid wire for gas shielded arc welding according to the present invention comprises: C: 0.02 to 0.10% by weight, Si: 0.30 to 1.00% by weight,
Mn: 1.20 to 2.00% by weight, Cu: 0.40 to 0.60% by weight, Ni: 1.40 to 2.30% by weight, Ti: 0.15 to 0.30% by weight, Mo: 0.1
5% by weight or less, the balance being Fe and unavoidable impurities, P is 0.015% by weight or less, S is 0.020% by weight.
Wt% or less, Cr is 0.15 wt% or less, Al is 0.0
30% by weight or less, Nb is 0.010% by weight or less, V is 0.010% by weight or less and N is 0.0100% by weight or less. When the content of Cu is [Cu], the content of Ni is [Ni], and the content of Ti is [Ti], A = 0.3 × [Cu]. +
The value of the parameter A represented by 0.5 × [Ni] + [Ti] is 1.00 to 1.45.

In the present invention, B is preferably contained in an amount of 0.0010 to 0.0080% by weight.

[0011]

Embodiments of the present invention will be described below in further detail. It is already well known that it is effective to remove Cr from conventional weather resistant components (Cu, Cr and Ni) and to add no Cr in order to improve salt damage resistance. However, by removing Cr, a rust film necessary for obtaining normal weather resistance is not sufficiently formed, and the weather resistance is reduced. In order to solve the above-mentioned problems, the inventors of the present application have proposed Cr
As a result of intensive studies on a method of forming a stable rust film instead of adding no, it is effective to add Ti and increase the content of Ni, and furthermore, Cu, Ni and Ti
It has been found that by setting the parameter having a variable as an appropriate range, not only salt damage resistance but also ordinary weather resistance becomes extremely good.

In order to obtain proper strength and sufficient low-temperature toughness, Mo, Al, Nb, V and N are not only individually limited, but also the total amount of Al, Nb, V and N is particularly limited. It has been found that regulating the upper limit is extremely effective.

The reasons for adding the components and the reasons for limiting the composition of the solid wire for gas shielded arc welding according to the present invention will be described below.

C: 0.02 to 0.10% by weight C is an element necessary for securing the strength of the weld metal. The minimum content of C in the wire effective for securing the strength of the weld metal for 400 to 520 N / mm ² grade steel is 0.02% by weight. On the other hand, if the content of C in the wire exceeds 0.10% by weight, CO explosion becomes excessive, the amount of spatter increases, and welding workability decreases. In addition, the hardenability increases and the strength becomes excessive. In addition, hot cracking and hydrogen cracking susceptibility also increase. For this reason, the upper limit of the content of C in the wire is 0.10% by weight. Therefore, the content of C in the wire is set to 0.02 to 0.10% by weight.

Si: 0.30 to 1.00% by weight Si is a main deoxidizing element and has an effect of improving strength. When the content of Si in the wire is less than 0.30% by weight, deoxidation becomes insufficient during large heat input welding, and blow holes are generated. In addition, the bead becomes less familiar and the appearance deteriorates. A preferable content of Si in the wire is 0.50% by weight.
It is. On the other hand, if the content of Si in the wire exceeds 1.00% by weight, the strength becomes excessive, the toughness is reduced, and the amount of slag generated is increased, and the continuous weldability is reduced. The preferable content of Si in the wire is 0.90% by weight. Therefore, the content of Si in the wire is set to 0.30 to 1.00% by weight. Preferably, the content of Si in the wire is 0.50 to 0.80% by weight.

Mn: 1.20 to 2.00 wt% Mn is a major deoxidizing element like Si, and has an effect of improving hardenability and increasing strength and toughness. When the content of Mn in the wire is less than 1.20% by weight, deoxidation becomes insufficient and blowholes are generated. Further, desired strength and toughness cannot be secured. In addition, the bead appearance is poor. The preferable content of Mn in the wire is 1.30% by weight. On the other hand, if the content of Mn in the wire exceeds 2.00% by weight, the strength becomes excessive, the slag amount increases, and the continuous weldability decreases. Thus, the upper limit of the content of Mn in the wire is 2.0
0% by weight. The preferred content of Mn in the wire is
1.7% by weight. Therefore, the content of Mn in the wire is set to 1.20 to 2.00% by weight. Preferably, the content of Mn in the wire is 1.30 to 1.70% by weight.

Cu: 0.40 to 0.60% by weight Cu is an indispensable element for weathering steel because it forms dense and stable rust on the surface. In the wire of the present invention to which Cr is not added, stable rust is not formed when the content of Cu in the wire is less than 0.40% by weight. On the other hand, when the content of Cu in the wire exceeds 0.60% by weight, the hot cracking resistance decreases and the toughness deteriorates. Therefore, the content of Cu in the wire is set to 0.40 to 0.60% by weight. In addition, the Cu content in the wire specified here is the total amount of the Cu content contained in the steel core wire and the Cu content of the plating when the wire is subjected to Cu plating.

Ni: 1.40 to 2.30% by weight Ni is also a very effective element for improving corrosion resistance. In the wire of the present invention to which Cr is not added, the content of Ni is made larger than that of the conventional wire in order to compensate for a decrease in corrosion resistance. It is also effective in improving toughness. If the content of Ni in the wire is less than 1.40% by weight, the corrosion resistance is insufficient. On the other hand, when the content of Ni in the wire exceeds 2.30% by weight, crack resistance is reduced, and spatter is increased to deteriorate workability. Therefore, the content of Ni in the wire is set to 1.40 to 2.30% by weight.

Ti: 0.15 to 0.30% by weight Conventionally, elements that contribute to weather resistance include Cu, Cr, and N.
Although i and P are known, it has been found that Ti has an effect of newly forming stable rust and is effective for improving weather resistance. If the content of Ti in the wire is less than 0.15% by weight, the effect of forming stable rust does not appear. Preferably, the content of Ti in the wire is 0.18% or more. On the other hand, if the content of Ti in the wire exceeds 0.30% by weight, the slag is excessively generated, although the corrosion resistance is increased, and the weldability is deteriorated, for example, droplets become large and spatter increases. In addition, the inclusions become excessive and the toughness decreases. Preferred T in the wire
The content of i is 0.25% by weight or less. Therefore, the content of Ti in the wire is set to 0.15 to 0.30% by weight. The preferred content of Ti in the wire is 0.15
To 0.25% by weight.

0.3 × [Cu] + 0.5 × [Ni] +
[Ti]: 1.00 to 1.45 Cu, Ni and Ti are not required to satisfy the respective allowable ranges, but are related to each other. It is necessary that the parameter A expressed by the equation 1 with the following equation as a variable satisfies the following equation 2.

[0021]

A = 0.3 × [Cu] + 0.5 × [Ni] + [Ti]

[0022]

1.00 ≦ A ≦ 1.45

The present inventors have found from a large number of experimental results that when the parameter A satisfies Equation 2, the corrosion resistance and weldability can be sufficiently improved.
When the value of the parameter A is less than 1.00, sufficient corrosion resistance in a non-salinity-corrosion environment cannot be obtained. On the other hand, when the value of the parameter A exceeds 1.45, weldability such as crack resistance and toughness decreases. Therefore, the range of the parameter A is 1.00 to 1.45.

Mo: 0.15% by weight or less Mo improves the hardenability and increases the strength. However, it decreases toughness. Furthermore, since the hydrogen cracking sensitivity increases due to the increase in strength, heat management such as preheating and post-heating is required, and the weldability deteriorates. Therefore, 40
In order to obtain a necessary and sufficient strength of 0 to 520 N / mm ² class and good low-temperature toughness and low-temperature cracking resistance, it is necessary to limit the content of Mo in the wire to 0.15% by weight or less. Therefore, the content of Mo in the wire is 0.15
% By weight or less. Further, if the content of Mo in the wire is 0.05% by weight or less, the toughness is further improved. From this, the preferable content of Mo in the wire is 0.0
5% by weight or less.

P: not more than 0.020% by weight P is an element having an extremely large adverse effect on welding. Highly deteriorates hot cracking resistance and low temperature toughness. Since P has a great effect on weather resistance, P is added to some steel plates, but because of poor weldability, it is necessary to suppress welding wires as much as possible. If the content of P in the wire is 0.020% by weight or less, there is no practical problem. Therefore, the upper limit is regulated to 0.020% by weight in consideration of economy. Therefore, the content of P in the wire is regulated to 0.020% by weight or less.

S: 0.020% by weight or less S, like P, also reduces hot cracking resistance and low-temperature toughness. When the content of S in the wire exceeds 0.020% by weight, these become remarkable. Therefore, the content of S in the wire needs to be 0.020% by weight or less. Preferably, the content of S in the wire is 0.015% by weight or less. However, since S has a function of increasing the interfacial tension of slag to cause coagulation, if the content of S is too low to be less than 0.008% by weight, the interfacial tension of slag decreases, and the entire bead surface becomes slag. Is disadvantageous in that an arc is less likely to be generated. For this reason, preferably, the lower limit of the S content in the wire is set to 0.008% by weight in consideration of the arc start property and the continuous weldability. Therefore,
The content of S in the wire is 0.020% by weight or less. The preferred content of S in the wire is 0.008 to 0.015% by weight.

Cr: 0.15% by weight or less Cr is effective for stable rust formation and is added to ordinary weather-resistant steel wires. However, considering the salt damage resistance, the smaller the better, the better. In the present invention, even if Cr is not added, there is no problem because sufficient weather resistance can be obtained even in a non-salted environment by adjusting other components. If the content of Cr in the wire is 0.15% by weight or less, it is acceptable without deteriorating the salt damage resistance. Therefore, the content of Cr in the wire is 0.15
Regulate to less than% by weight. However, it is preferable that the content of Cr in the wire be regulated to 0.05% by weight or less in an environment where salt corrosion resistance is extremely severe.

Al: 0.030% by weight or less, Nb: 0.
010% by weight or less, V: 0.010% by weight or less, N:
0.0100% by weight or less Al, Nb, V and N are elements that extremely deteriorate toughness. In particular, Al, Nb, V and N significantly increase strength, increase hydrogen cracking susceptibility, and extremely deteriorate weldability. N also causes a pore defect such as a blow hole. For this reason, it is desirable to remove these elements as much as possible. Therefore, the content of Al in the wire is 0.030% by weight or less, the content of Nb is 0.010% by weight or less, and the content of V is 0.010% by weight or less.
% By weight and the N content is 0.0100% by weight or less. Preferably, the Al content in the wire is 0.020% by weight or less, the Nb content is 0.005% by weight or less, the V content is 0.005% by weight or less, and the N content is 0.00.
70% by weight or less.

Al, Nb, V and N: 0.040 in total
As described above wt% or less, Al, Nb, V and N are preferably reduced as much as possible respectively. Further, it is necessary to regulate the total amount of Al, Nb, V and N. Al, Nb, V and N
If the total amount is not more than 0.040% by weight, good performance cannot be obtained. Therefore, Al, N in the wire
b, V and N are regulated to 0.040% by weight or less in total. Preferably, the total amount of Al, Nb, V and N in the wire is regulated to 0.030% by weight or less.

B: 0.0010 to 0.0080% by weight B functions as a nucleus for forming ferrite, and is effective in improving the toughness in order to refine the amount of crystals. In particular, it is well known that the effect is greatly enhanced by simultaneous addition with Ti. In the present invention, since Ti is added as an effective element for forming stable rust effective for weather resistance, it is possible to increase toughness by further adding B. When the content of B in the wire is less than 0.0010% by weight, it does not contribute to improvement in toughness. On the other hand, when the content of B in the wire exceeds 0.0080% by weight, hot cracking resistance deteriorates. Therefore, the content of B in the wire is
0.0010 to 0.0080% by weight.

[0031]

EXAMPLES Hereinafter, examples of the solid wire for gas shielded arc welding according to the present invention will be specifically described in comparison with comparative examples out of the scope of the present invention. FIG. 1 is a sectional view showing a groove shape of a member to be subjected to gas shielded arc welding according to these examples and comparative examples.

First, a steel sheet was welded using wires having the compositions shown in Tables 1 to 4 under the welding conditions shown in Table 5 below. As shown in FIG. 1, a backing material 3 is disposed on a back surface of two steel plates 1 having a thickness of 50 mm, each having an end formed on a slope, opposed to each other with a gap of 5 mm. did. Then, the weld metal 2 was formed by performing gas shield arc welding on the formed groove. In this case, the groove shape is V-shaped and the groove angle is 3
5 °.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

Next, the obtained weld metal was subjected to a room temperature tensile test, a Charpy impact test, and a weather resistance evaluation test, and a sensory evaluation of continuous weldability, weld cracking and blowhole (B. H.) and the sensory evaluation of the spatter generation amount was performed and evaluated.
In addition, the sampling position of the tensile test and the Charpy impact test specimen is 10 mm from the surface of the steel sheet and at the center of the welded portion.
The weather resistance was evaluated by a two-year long-term atmospheric exposure test. Two locations were set up on the mountainous area (100km inland from the coast) and on the sea crossing road, and they were installed facing south.

As a result of the evaluation, the room temperature tensile test of the weld metal was judged to have passed a tensile stress (TS) of 530 to 650 N / mm ² . A more preferred range is 530 to 620 N / mm ² . Also, 0.2
Proof stress (PS) is 400 to 560%
N / mm ² was accepted. A more preferred range is 430
To 510 N / mm ² . Furthermore, the Charpy impact test showed that the absorbed energy at -25 ° C (vE-25 ° C) was 4
Those with 5 J or more were judged to be acceptable. A more preferred range is 100 J or more. In the sensory evaluation of continuous weldability,
Very good ones were evaluated as good, good ones as poor, and poor ones as bad. Two types of weathering performance evaluation tests were performed, that is, the presence or absence of weld cracks and blowholes (BH) by X-ray radiographic measurement, and the sensory evaluation of spatter generation and appearance. The weather resistance was evaluated based on the reduction in sheet thickness. In a non-salinity-corrosive environment, 0.05 mm or less was regarded as acceptable. In the salt damage corrosion environment of 0.08 mm or less, it was judged as acceptable. A more preferable range is 0.05 mm or less. Tables 6 to 9 show the evaluation results.

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

[Table 8]

[0043]

[Table 9]

As shown in Tables 6 to 9 above, Example N
o.1 to 14 have good weatherability with little reduction in sheet thickness in both salt-corrosion environment and non-salinity environment because each wire component satisfies the specified range specified in the claims of the present invention. I was Further, the tensile strength of the weld metal was appropriate and the low-temperature toughness was also good. Very good weldability,
No welding defects such as cracks or blow holes were generated, the arc was stable, the spatter was small, the bead appearance was good, and the slag was small, so that the continuous weldability was good.

On the other hand, in Comparative Examples 15 to 29, the desired performance could not be obtained because the chemical composition of the wire did not satisfy the claims of the present invention.

Comparative Example No. 15 shows that the content of C exceeds the range of the present invention and is too large, so that the quenchability is increased and the strength becomes excessive, thereby causing hydrogen cracking. Toughness decreased. In addition, the spatter amount due to the CO explosion also increased due to the large C content. Further, C
If the contents of u, Ni and Cr exceed the range of the present invention and are too large, the toughness is also deteriorated, and hot cracking occurs. Furthermore, since Cu, Ni and Cr are contained in a large amount beyond the scope of the present invention, the amount of reduction in sheet thickness in a conventional non-salinity-corrosive environment is small. In the environment, the amount of thickness reduction was large, and sufficient weather resistance was not obtained.

Comparative Example No. 16 is based on JIS Z 3315
One of the conventional wires for weather resistant steel belonging to YGA-50W
One. The content of Cu and Ni is smaller than the range of the present invention, while the content of Cr exceeds the range of the present invention, and the content of Ti is smaller than the range of the present invention. The amount of reduction in sheet thickness is very large, and the weather resistance is poor. Naturally, in a conventional non-salinity-corrosive environment, the amount of reduction in sheet thickness is small, and good weather resistance is obtained. Further, since the total amount of Al + Nb + V + N exceeds the range of the present invention, sufficient low-temperature toughness has not been obtained.

Comparative Example No. 17 is based on JIS Z 3315
One of the conventional wires for weather resistant steel belonging to YGA-50W
This is a wire having a composition from which Cr has been removed. By not containing Cr, the thickness reduction in a salt-corrosion environment was reduced and improved. On the other hand, since it does not contain Cr which has contributed to the formation of stable rust in a non-salinity-corrosive environment, stable rust is not formed, and the amount of reduction in sheet thickness in this environment increases.
Weathering performance deteriorated. Further, since the total amount of Al + Nb + V + N exceeds the range of the present invention, sufficient low-temperature toughness has not been obtained.

Comparative Example No. 18 is based on JIS Z 3315
One of the conventional wires for weather resistant steel belonging to YGA-58W
This is a wire from which Cr has been removed. As in Comparative Example No. 17, the absence of Cr improves the weather resistance in a salt-corrosion environment. On the other hand, the Ni content is less than the range of the present invention, and although Ti is slightly added, since the content is less than the range of the present invention, the weather resistance in a non-salt damage corrosion environment is increased. Sex has declined. Also, Mo
Was added in excess of the range of the present invention, so that the strength of the weld metal became abnormally high and hydrogen cracking occurred. Further, the toughness was also reduced. Similarly to Comparative Examples Nos. 16 and 17, the total amount of Al + Nb + V + N exceeded the range of the present invention, and further, the contents of P and S were higher than the range of the present invention, and did not cause hot cracking. One of the causes of lowering the low temperature toughness.

Comparative Example No. 19 was insufficient in strength because the content of C was less than the range of the present invention. Comparative Example No.
In No. 20, since the Si content was lower than the range of the present invention, the strength was insufficient, blowholes were generated due to insufficient deoxidation, and spatter increased. In addition, the adaptability became poor, and the bead appearance deteriorated. Furthermore, the content of Cu is lower than the range of the present invention, the sheet thickness reduction is large in both the salt damage corrosion environment and the non-salt damage corrosion environment, and sufficient weather resistance is not obtained. Furthermore, since the content of Ni exceeds the range of the present invention and is excessive, and the value of the parameter A also exceeds the range of the present invention, weldability deteriorates, spatter increases, generation of hot cracks, This led to a decrease in toughness.

In Comparative Example No. 21, the strength was excessive because the contents of Si and Mn exceeded the range of the present invention. In addition, the slag amount increased, the continuous weldability decreased, and the efficiency was poor. The contents of P and S were also significantly outside the range of the present invention, and hot cracking occurred, and the low-temperature toughness also deteriorated. Further, although the respective values of Cu, Ni and Ti satisfy the range of the present invention, since the value of the parameter A is lower than the range of the present invention, the weather resistance in a non-salinity corrosion environment is insufficient. There was a large amount of thickness reduction.

In Comparative Example No. 22, the content of Mn was less than the range of the present invention, deoxidation was insufficient, blowholes were generated, and the strength of the weld metal was low. Also, the toughness was reduced. Further, Cu and Ti are within the scope of the present invention, but since the content of Ni is less than the scope of the present invention, the weather resistance in a non-salinity-corrosion environment is insufficient, and the thickness reduction is large. Was.

In Comparative Example No. 23, the Cr content exceeds the upper limit of the range of the present invention, so that the weather resistance in a salt damage corrosion environment is insufficient. On the other hand, since the content of Cr is less than 0.50% by weight, which is the minimum Cr content that can provide normal (non-salt-corrosion corrosion environment) weather resistance specified in JIS Z 3315, weather resistance in a non-salt-corrosion environment is also low. There was a shortage, and the amount of thickness reduction was large in both environments. Although Cu, Ni and Ti each satisfy the range of the present invention, since the value of the parameter A exceeds the range of the present invention, the toughness decreases,
Hot cracking occurred. Further, since the Al content exceeded the range of the present invention and was excessive, the strength became too high, and hydrogen cracking occurred. Furthermore, since the total amount of Al + Nb + V + N exceeds the range of the present invention, the toughness is reduced.

In Comparative Example No. 24, the content of Ti exceeded the upper limit of the range of the present invention, and large spatters were generated in large quantities, resulting in poor workability. In addition, the amount of slag also increased, impairing continuous weldability. Further, the content of B was beyond the range of the present invention, and hot cracking occurred. Furthermore, the V content was beyond the range of the present invention, and the strength became excessive and the toughness was lowered.

In Comparative Example No. 25, although the contents of Cu, Ni and Ti each satisfied the range of the present invention, the value of parameter A exceeded the range of the present invention. And hot cracking occurred.

In Comparative Example No. 26, the contents of Nb and N exceeded the range of the present invention, and hydrogen cracking occurred due to excessive strength and the toughness was low. Further, since the N content exceeded the range of the present invention and was excessive, blowholes occurred.

In Comparative Example No. 27, since Mo and N exceeded the range of the present invention, the strength became excessive and hydrogen cracking occurred, and the total amount of Al + Nb + V + N exceeded the range of the present invention. Has contributed to the decline.

In Comparative Example No. 28, the contents of Nb and V exceeded the range of the present invention, the strength became excessive, and hydrogen cracking occurred. Further, since the content of Al + Nb + V + N was beyond the range of the present invention, it promoted a decrease in toughness.
Further, since the content of Cu is also beyond the scope of the present invention,
Hot cracking occurred while deteriorating toughness.

Comparative Example No. 29 is JIS Z 3315
One of the wires of YGA-50P. This wire is free of Ni and Cr. Since Ni is not added, the corrosion resistance of the bare specification is insufficient in both the non-salt damage environment and the salt damage environment. Since it contains Cr, it is ineffective especially in a salt damage corrosion environment. Also,
Since the Al content exceeded the range of the present invention, the strength became excessive, and the toughness was reduced and hydrogen cracking occurred.

[0060]

As described in detail above, in the present invention,
By stipulating the chemical composition of each solid wire for gas shielded arc welding independently and strictly defining the total amount and combination of each wire composition, it was possible to achieve a non-salt damage environment, which was difficult in the past. In an environment with a salt damage corrosive environment, weather resistance can be extremely well compatible. As a result, the weather-resistant steel wire, which conventionally had to be properly used in a coastal area (salt-corrosion environment) and a mountainous area (non-salt-corrosion environment), can cover all environments with only this wire. Further, good corrosion resistance can be obtained even in a middle area between a coastal area and a mountainous area, that is, an area where salt damage corrosion and non-salt damage corrosion progress simultaneously. Therefore, a great industrial value can be obtained.

Further, the solid wire for gas shielded arc welding of the present invention can be used not only for weather resistance but also for strength, low temperature toughness, crack resistance, pore defect resistance, welding workability such as spatter and slag, and bead appearance. A good weld metal can be obtained because of the excellent wire. Therefore, weatherable steel is the most important structure used most and can be used for bridges where reliability is important.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a groove shape of a member to be gas-shielded arc welded according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1: steel material 2: weld metal 3: backing material

Claims (2)

[Claims] 1. C: 0.02 to 0.10% by weight, S
i: 0.30 to 1.00% by weight, Mn: 1.20 to 2.00% by weight, Cu: 0.40 to 0.60% by weight,
Ni: 1.40 to 2.30% by weight, Ti: 0.15 to 0.30% by weight, Mo: 0.15% by weight or less, the balance being Fe and unavoidable impurities, and P being 0.
015% by weight or less, S is 0.020% by weight or less, Cr is 0.15% by weight or less, Al is 0.030% by weight or less, N
b is regulated to 0.010% by weight or less, V is regulated to 0.010% by weight or less, and N is regulated to 0.0100% by weight or less.
The Al, Nb, V and N are regulated to a total amount of 0.040% by weight or less.
Is [Ni] and the content of Ti is [Ti], A = 0.3 × [Cu] + 0.5 × [Ni] +
A solid wire for gas shielded arc welding, wherein a value of a parameter A represented by [Ti] is 1.00 to 1.45. 2. The solid wire for gas shielded arc welding according to claim 1, wherein B is contained in an amount of 0.0010 to 0.0080% by weight.