JPH0747473A - Carbonic acid gas pulse arc welding method - Google Patents

Abstract

PURPOSE:To remarkably lower spattering in carbonic acid gas pulse arc welding by a middle current or a large current by contriving an optimal combination of a welding current parameter and a chemical component of a wire, based on a pulse condition that one pulse becomes one droplet. CONSTITUTION:Welding is executed by using a welding solid wire whose chemical components consists of 0.01-0.05% C : 0.5-3% (Si+Mn) : 0.05-0.4% (Ti+Al), Fe of the remaining part and inevitable impurities, and also, using a square wave pulse for satisfying welding current parameters of (a) 400-550A peak current Ip : (b) 5-15ms peak current period : (c) 30-100A base current IB : (d) 5-35ms base current period TB : and (e) 200-350A average current Iav.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon dioxide gas pulse arc welding method capable of reducing the amount of spatter generated by optimally combining the chemical composition of a welding wire and the pulse conditions.

[0002]

2. Description of the Related Art Carbon dioxide arc welding, which uses carbon dioxide as a shielding gas, can be carried out at a lower cost and is more resistant to defects than welding using a mixed gas mainly containing an inert gas such as Ar or He. Since it is excellent, it is widely applied in the welding of low alloy steels including mild steel. However, in the carbon dioxide arc welding method using a thyristor power source, compared to the case of using other shield gas,
This has a drawback that the arc becomes unstable and spatters are irregularly generated mainly due to short-circuit transfer, resulting in a large amount of spatters.

From the viewpoint of eliminating the above drawbacks, droplets are synchronously transferred using a pulse power source (1 pulse 1 droplet), but there are the following problems. It was That is, in carrying out the carbon dioxide pulse arc welding, in the case of droplet transfer in the base current period of the low current to medium current region, since the short-circuit transfer form is accompanied, the amount of spatter tends to increase, Further, it becomes difficult to apply it in a large current region. On the other hand, in the case of the transfer form due to droplet detachment during the peak current period, it can be applied in the medium current to large current region and almost no short circuit transfer occurs, but it cannot be said that controlling the pulse current is sufficient. However, spattering still occurs due to other factors. Other factors that may cause the generation of spatter include the wire composition and the like, but hitherto no technique has been proposed for reducing spatter in consideration of the wire composition.

[0004]

SUMMARY OF THE INVENTION The present invention has been made under these circumstances, and its purpose is to provide 1 pulse 1 pulse.
Based on the pulse conditions that form droplets, by optimizing the combination of welding current parameters and wire chemical components,
It is to achieve a large reduction in spatter in carbon dioxide pulse arc welding at medium to large currents.

[0005]

Means for Solving the Problems According to the present invention capable of achieving the above object, the chemical component is C: 0.01 to 0.05%,
(Si + Mn): 1.5 to 3%, (Ti + Al): 0.
A solid wire for welding consisting of 05 to 0.4% and the balance Fe and unavoidable impurities is used, and the following (a) to
The carbon dioxide gas pulse arc welding method is characterized in that the welding is performed using a rectangular wave pulse satisfying the welding current parameter (e).

(A) Peak current I _P : 400 to 550 A (b) Peak current period T _P : 5 to 15 ms (c) Base current I _B : 30 to 100 A (d) Base current period T _B : 5 to 35 ms ( e) Average current I _av : 200 to 350 A

[0007]

The present invention is constructed as described above, but it has been found that the amount of spatter generation can be remarkably reduced by the optimum combination of the chemical composition of the solid wire for welding and the pulse condition (ie, welding current parameter). Was completed. First, the reasons for limiting the chemical composition of the solid wire for welding used in the present invention are as follows.

C: 0.01-0.05% FIG. 1 is a graph showing the relationship between the amount of C in the entire wire and the frequency of spatter generation. Spatter in FIG. 1 means the spatter generated from the molten pool. is there. As is clear from FIG. 1, when the amount of C exceeds 0.05%, the amount of spatter generated from the molten pool increases. On the other hand, if the amount of C is less than 0.01%, the strength of the deposited metal decreases, which is not suitable. The preferable range of the amount of C is about 0.02 to 0.05%.

(Si + Mn): 1.5 to 3% FIG. 2 is a graph showing the relationship between the (Si + Mn) amount of the entire wire and the frequency of spatter generation. Spatter in FIG. It means the spatter that sometimes occurs. As is clear from FIG. 2, (Si + M
If the amount n) is less than 1.5%, spattering when the droplets are released increases. On the other hand, if it exceeds 3%, the toughness of the deposited metal is lowered, the wire becomes hard, and the wire drawability and the like are affected.
The preferable ranges of Si and Mn are Si: 0.65 to 0.65, respectively.
It is 0.9% and Mn: 1.4 to 1.6%, and it is more effective for the control of sputtering if the respective amounts of Si and Mn are adjusted within the above total amount range.

(Ti + Al): 0.05-0.4% FIG. 3 is a graph showing the relationship between the (Ti + Al) amount of the entire wire and the frequency of spatter generation. Spatter in FIG. This is the meaning of spatter that occurs when droplets separate. As is clear from FIG. 3, (Ti + A
If the amount of l) is less than 0.05%, the amount of spatter at the time of droplet separation increases. On the other hand, if it exceeds 0.4%, the toughness of the deposited metal decreases, the wire becomes hard, and the wire drawability is adversely affected. The preferred ranges of Ti and Al are Ti:
0.14 to 0.2%, Al: 0.02 to 0.1%. If the amounts of Ti and Al are adjusted within the above total amount range, it is more effective in suppressing spatter. is there.

The chemical composition of the solid wire for welding used in the present invention is as described above, and the balance is Fe and inevitable impurities. To achieve the object of the present invention, the welding current is set as described above. Welding must be performed using square wave pulses that satisfy the parameters. Next, the reason for setting these parameters will be described. The position of each parameter of the rectangular wave pulse is as shown in FIG.

Peak current I _P : 400 to 550 A If the peak current is less than 400 A, the electromagnetic pinch force is weak and the detachment of droplets is not promoted, so that droplets are less likely to be transferred per pulse and spatter occurs. Further, when the peak current exceeds 550 A, the pinch force for originally releasing the droplet acts in the direction of pushing up the droplet and is similarly unstable.

Peak current period T _P : 5 to 15 ms If the peak current period T _P is less than 5 ms, the period is short and sufficient melting is not performed, resulting in n pulse 1 droplet transfer. On the contrary, if it exceeds 15 ms, one pulse n droplet transfer occurs, and the droplet is not stable at this time as well.

Base current I _B : 30 to 100 A When the base current I _B is less than 30 A, a short circuit easily occurs between the droplet and the molten pool during the base period, which causes a large amount of spatter. Although it has a role of stabilizing the droplet during the base period, when the base current I _B exceeds 100 A, it is always affected by a strong arc, and stable droplet transfer is unlikely to occur.

Base current period T _B : 5 to 35 ms If the base current period T _B is less than 5 ms, the droplet is difficult to stabilize because the period is short. Also, the base current period T _B
Is more than 35 ms, the base period becomes too long, so that a short circuit easily occurs between the droplet and the molten pool during the period.

Average current I _av : 200 to 350 A When the average current I _av is less than 200 A, the arc length is stable only when it is longer than usual, and arc breakage easily occurs. If it exceeds 350 A, the force of pushing up the upward droplet due to the pinch force of the arc is increased, and the phenomenon that the droplet or a part thereof is directly scattered as spatter occurs. Therefore, the average current needs to be in the range of 200 to 350A. Here, the average current means the above I _P , T _P , I _B ,
It is a value defined by the following equation (2) according to T _B.

I _av = (I _P × T _P + I _B × T _B ) / (T _P + T _B ) ... (2)

The object of the present invention is achieved by the optimum combination of the chemical composition of the solid wire for welding and the welding current parameter as described above, and the specific surface area defined by the above formula (1) is set to 0. A value of 01 or less is more effective for reducing spatter. That is, if the value of the specific surface area exceeds 0.01, the electrical conductivity of the wire is lowered, and the effect of hindering the generation of arc is increased, and the spatter is increased. Further, when considering reduction of spatter, 0.001 or less is desirable.

Here, the specific surface area of the wire is the apparent area of the measurement portion where the actual surface area of the wire surface is measured, Sm.
(Mm ² ), the actual surface area of the wire surface of the measurement part is Sa (m
m ² ) is defined by the following formula (see FIG. 5).

Wire specific surface area = (Sa / Sm) -1

The apparent area Sm of the measuring portion is
It is the area represented by (length x width) when the measurement portion is developed on a plane. In the present invention, the actual surface area of a portion of 500 μm × 600 μm (300000 μm ² ) was measured after the measurement portion was developed on a plane. The specific surface area of the wire is measured by the method under the following conditions.

Sampling method: Approximately 20 mm so as not to scratch the product wire wound on the spool as much as possible
To remove it from any three locations, in an organic solvent that does not corrode the metal surface, such as petroleum ether, acetone, carbon tetrachloride, CFCs, or depending on the type of lubricant used in the processing process. Ultrasonic cleaning with the most suitable liquid (hot water or other degreasing liquid) removes impurities such as stains and oils adhering to the wire surface. Ultrasonic cleaning is performed one by one so that the wires do not rub against each other and scratch.

In the production of wire, it is noted that among the flaws received from the die by wire drawing, the various parts of the equipment and the contact between wires, it is noted that flaws, abrasion marks, etc. are not generated as much as possible. In that sense, the specific surface area value is measured by selecting a portion having no flaw.

Measurement position: One arbitrary cross section of one sample
The measurement is performed at three points shifted by 20 degrees, and the simple average of the measured values of nine points in total of three samples is used. Measurement magnification: 150 times (constant regardless of wire diameter). As the measuring device, for example, ERA-800 manufactured by Elionix Co., Ltd.
0 is mentioned.

The solid wire for welding used in the present invention may be Cu-plated on its surface, and the Cu plating amount is usually 0.15 to the total weight of the wire.
Although it is about 0.3%, in the welding solid wire of the present invention, it is desirable to set it to about 0.25 to 0.3% in consideration of the energization amount.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification of the design of the present invention can be made without departing from the spirit of the preceding and the following. It is included in the technical scope.

[0027]

[Examples] The state of spatter generation was investigated when welding was carried out under conditions in which various combinations of welding current pulse conditions and wire compositions shown in Tables 1 and 2 were changed. The results are shown in Table 1.
And also shown in Table 2. The evaluation criteria for the spatter generation status are as follows. The specific surface area is 1-36
No. 0.001, No. 37 is 0.009,
No. The value of 38 was 0.012. As is clear from Tables 1 and 2, it is understood that the ones satisfying the requirements specified in the present invention can achieve stable 1 pulse / 1 droplet transfer and can reduce the spatter generation amount. .

(Evaluation criteria for spatter generation status) ◎: Very good ○: Good ◇: Almost good △: Small particle spatter adhered ×: Large particle spatter adhered (-): Arc breakage occurred

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

The present invention is constituted as described above, and by the optimum combination of the pulse conditions and the welding wire, the spatter and the droplet detachment from the molten pool, which remained as the generation mode even when the pulse current is applied. The spatter during the subsequent re-arc could be controlled. Further, since the spatter is reduced, the total cost can be reduced and the efficiency can be improved by reducing the spatter removal time in the actual welding line.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of C in the entire wire and the frequency of spatter generation.

FIG. 2 is a graph showing the relationship between the (Si + Mn) amount of the entire wire and the frequency of spatter generation.

FIG. 3 is a graph showing the relationship between the (Ti + Al) amount of the entire wire and the frequency of spatter generation.

FIG. 4 is a waveform diagram for explaining a welding current parameter defined in the present invention.

FIG. 5 is a diagram for explaining a specific surface area defined by the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaharu Sato, Inoue Miyazaki, Fujisawa-shi, Kanagawa 100-1 Urakawachi, Ltd. Kobe Steel, Fujisawa Plant (72) Inventor Fuseki Koshiishi Miyazawa, Kawasaki, Kanagawa Prefecture 100-1 share company inside the Kobe Steel Fujisawa Plant (72) Inventor Takaaki Ito Urakawachi, Miyamae, Fujisawa City, Kanagawa Prefecture 100-1 share inside the Kobe Steel Fujisawa Plant

Claims (2)

[Claims] 1. The chemical component is C: 0.01 to 0.05%.
(Mean of weight%, same below), (Si + Mn): 1.5
~ 3%, (Ti + Al): 0.05-0.4%, balance F
A carbon dioxide pulse arc welding method characterized by using a solid wire for welding comprising e and unavoidable impurities and performing welding using a rectangular wave pulse satisfying the following welding current parameters (a) to (e). (A) the peak current I _P: 400~550A (b) the peak current duration T _P: 5~15ms (c) the base current I _B: 30~100A (d) the base current period T _B: 5~35ms (e) Mean Current I _av : 200-350A 2. The carbon dioxide pulse arc welding method according to claim 1, wherein a welding solid wire having a specific surface area of the wire surface of 0.01 or less defined by the following formula (1) is used. Specific surface area = [(Sa / Sm) −1] (1) Sm: apparent area of the measurement part where the actual surface area of the wire surface is measured (mm ² ) Sa: actual surface area of the wire surface of the measurement part ( mm ² )