JPH0645076B2 - Gas shield arc welding wire for zinc plated steel plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas shielded arc welding wire for galvanized steel sheet.

(Prior Art and Problems Thereof) In the fields of automobiles, housing construction materials, etc., galvanized steel sheets having excellent rust-preventive properties tend to be used frequently in order to prolong the life of products. A joint is formed by spot welding on a thin galvanized steel sheet, and a gas shield arc welding is performed using a welding wire on a spot where the spot welding cannot be performed or on a thick galvanized steel sheet.

However, when the galvanized steel sheet is exposed to a high temperature during welding, the zinc in the plating layer melts and becomes zinc (Zn) vapor, which causes welding defects such as blow holes and pits in the welded portion. In order to prevent the formation of blow holes and pits in the welded portion, welding is conventionally performed after mechanically removing the plating layer of the welded portion of the galvanized steel sheet. Although this method is an effective method for preventing welding defects, it is time-consuming and inefficient.

The present invention has been made to solve such a problem, and is used for gas shielded arc welding of galvanized steel sheet, and there is no need for pretreatment such as removal of the galvanized layer and welding of blowholes, pits, etc. An object is to provide a welding wire with few defects.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the inventors of the present invention made various trials of welding wires having various chemical components and, as a result of repeating the experiment, as a result, a component range in which blowholes or pits are rarely generated. Found.
The present invention has been made based on such findings, the gas shielded arc welding wire for galvanized steel sheet of the present invention,
% By weight, C: 0.15% or less, Si: 0.50 to 1.00%, Mn: 0.
10 to 0.50%, P: 0.020% or less, S: 0.030% or less, and the balance being substantially Fe.

Preferably, it is desirable to contain one or two or more kinds selected from Ti: 0.60% or less, A1: 0.80% or less, Ni: 5.0% or less, and Cu: 1.0% or less by weight%.

More preferably, the lower limit of the S content is regulated to 0.010%.

(Function) The function of the chemical components contained in the welding wire of the present invention and the reason for limiting the component range will be described below.

C: 0.15% or less If the C content increases, the toughness of the welded portion deteriorates and cracks easily occur, so the upper limit was set to 0.15% or less.

Si: 0.50 to 1.00%, Mn: 0.10 to 0.50% Si and Mn are both powerful deoxidizers. Below the lower limit, blowholes increase due to insufficient deoxidation, and above the upper limit, blowholes due to zinc vapor. Etc. will increase.

P: 0.020% or less As with C, P easily cracks when its content increases, so an upper limit was set and P was restricted to 0.020% or less.

S: 0.030% or less, preferable lower limit value 0.010% When the content of S is within the predetermined range, the number of blowholes and pits is small, and when the content exceeds the upper limit, the number of blowholes and pits sharply increases. However, since the generation of blowholes and pits tends to increase as the amount of S decreases, it is desirable to control the lower limit to 0.010%. Ti, A1, Ni, Cu When these elements are added Both have the effect of suppressing the formation of blowholes and pits, but each upper limit (T
i: 0.60%, A1: 0.80%, Ni: 5.0%, Cu: 1.0
%), The excessive addition of blowholes and pits increases. A1, Ni and Cu increase the solid solubility limit of Zn and suppress the generation of Zn vapor. Further, when the amount of Ni exceeds the upper limit value, cracking tends to occur, and since Ni is a rare metal, the upper limit is regulated for economic reasons. If the amount of Cu exceeds the upper limit, the workability of the welding wire is impaired, which is not preferable.

(Example) Next, the Example of the gas shielded arc welding wire for galvanized steel sheets which concerns on this invention is described.

Table 1 shows the chemical composition and welding test results of the wire of the present invention and the comparative wire. Each of the test wires having a wire diameter of 1.2φ was manufactured by melting steel having the components shown in Table 1. Then, using each test wire, welding current: 200 A, welding speed: 80 cm / mi
n, Shirutogasu: plate thickness at the welding condition of CO ₂ 20 / min
Table 2 shows the number of blow holes and the number of pits in a bead having a length of 100 mm after counting the fillet welds on a 2.3 mm 45/45 unit weight galvanized steel sheet.

The sample wires NO. 7 and 8 which are comparative wires have Si amounts outside the lower and upper limits, and the sample wires NO. 9 and 10 have Mn amounts outside the lower and upper limits. The test wire Nos. 11 to 15 are S, respectively.
The amount, the amount of Ti, the amount of A1, the amount of Ni, and the amount of Cu all deviate from the upper limits. The number of blow holes and the number of pits of these comparison wires are obviously different from those of the wires of the present invention, and the numbers of the comparison wires are remarkably large.

The wires of the present invention (test wires Nos. 1 to 6) had blowholes of 0 to 6, and the pits of all the test wires were 0, and the test results were sufficiently obtained for practical use. . If one or more of Ti, A1, Ni, Cu are added to the wire (test wire No. 3 to 6), the number of blow holes is 0.
It is reduced to ~ 3, and there are few welding defects compared with the test wire No.1. However, the number of blowholes in the test wire with S content of 0.010% or less tends to increase (test wire
Comparison of No. 2 and test wire No. 1, and test wire No. 5
And the test wire No. 4 or 6), the lower limit of the S amount is 0.0
It is desirable to regulate to 10%.

(Effects of the Invention) As described in detail above, according to the gas shielded arc welding wire for galvanized steel sheet of the present invention, C: 0.15% by weight%.
Hereinafter, Si: 0.50 to 1.00%, Mn: 0.10 to 0.50%, P: 0.
020% or less, S: 0.030% or less, and the balance substantially consisting of Fe, preferably Ti: 0.60% or less by weight, and A
1: 0.80% or less, Ni: 5.0% or less, Cu: 1.0% or less, one or more kinds selected from are contained, and more preferably, the lower limit of the S content is set to 0.010%. Therefore, even if the galvanized steel sheet is welded without performing pretreatment such as removal of the galvanized layer, it is possible to extremely reduce the occurrence of welding defects such as blow holes and pits.

Claims (3)

[Claims] 1. C: 0.15% or less by weight%, Si: 0.50 to 1.00
%, Mu: 0.10 to 0.50%, P: 0.020% or less, S: 0.030
% Or less, and the balance substantially consisting of Fe. A gas shielded arc welding wire for galvanized steel sheet. 2. Further, Ti: 0.60% or less by weight% and A1: 0.
Gas shield for galvanized steel sheet according to claim 1, containing one or more selected from 80% or less, Ni: 5.0% or less, and Cu: 1.0% or less. Arc welding wire. 3. The gas shielded arc welding wire for galvanized steel sheet according to claim 1 or 2, wherein the lower limit of the S content is restricted to 0.010%.