JPH01289595A - welding wire - Google Patents

Abstract

PURPOSE:To remarkably improve an arc starting property and to prevent the welding defect at the arc welding time by a robot, etc., by contg. specified metal elements in the ferrous alloy welding wire utilized in gas shield arc welding. CONSTITUTION:The structure contg. the metal of a low m.p. of <=650 deg.C m.p. and of a low b.p. of <=1,750 deg.C b.p. and reducing the surface tension of a molten iron at 2-20 times an O content in weight % is taken. The arc starting property of are welding time using this welding wire can be made remarkably good and it is enabled to contribute largely for the improvement of working efficiency and that of quality.

Description

[Detailed description of the invention] [Purpose of the invention]

(Field of Industrial Application) The present invention relates to an iron-based alloy welding wire used in gas-shielded arc welding such as C02 and MAG welding, and in particular an arc welding wire that can significantly improve the arc startability of gas-shielded arc welding. This relates to wires for use. (Prior Art) In recent years, robotization has spread rapidly in the welding industry, and the adoption rate is particularly high in industries such as automobiles. The main welding methods are spot resistance welding and gas shielded arc welding such as C02 and MAG welding (such gas shielded arc welding is
For example, "3rd Edition Steel Handbook" Volume ■ Secondary Processing/Surface Treatment/Heat Treatment φ Welding May 31, 1980 Editor
The Iron and Steel Institute of Japan, pages 615 to 618. ). (Problems to be Solved by the Invention) Particularly in arc welding using robots, when many parts are welded continuously or intermittently in a certain order, poor arc startability may cause sticking, burn-out, etc. This causes problems such as defects in the bead shape at the welding start point, or in worse cases, the welding cannot be completed, which significantly reduces the work efficiency and causes quality defects. Previous attempts have been made to solve these problems, such as adding a special control circuit to the welding power source to optimally control the heat input at arc start, but none of them have had their problems. It has not yet been fully resolved. (Object of the Invention) The present invention has been made to solve the conventional problems as described above, and it is possible to control the arc by adjusting the components of the welding wire without providing a special control circuit to the welding power source. The object of the present invention is to provide a welding wire that significantly improves startability, prevents welding defects during arc welding by robots, etc., and improves efficiency.

[Structure of the invention]

(Means for Solving the Problems) The welding wire according to the present invention has a melting point of 650
O
It is characterized by having a structure in which the content is 2 to 20 times the content, and this structure of the welding wire is a means for solving the above-mentioned conventional problems. In one embodiment of the present invention, the welding wire has, in weight %,
C: 0.15% or less, Si: o, 3-2.4%, M
n: 0, 4-2, 0%, 0:0.002-0.
04%, and Bi, Sb. 0 in total of one or two or more selected from Pb
．． In a more preferred embodiment of the present invention, the welding wire contains 1% by weight, C: 0.15% or less, and the remainder consists of Fe and impurities.
Si: 1.2-1.8%, Mn: 0.4-0.8%, O
: 0.002 to 0.04%, and 0.00 in total of one or more selected from Bi, Sb, and Pb
It contains 4 to 0.8%, with the remainder consisting of Fe and impurities. The welding wire according to the present invention has the above-mentioned configuration, and in order to significantly improve the arc startability, a characteristic metal element is added to the wire at a constant ratio based on 0 content. The present invention aims to provide a welding wire with good arc startability. Hereinafter, the present invention will be explained in detail. First, the welding wire according to the present invention contains 0% by weight of a metal element that has a low melting point of 650°C or less and a low boiling point of 1750°C or less and reduces the surface tension of molten iron. It is made to contain 2 to 20 times as much to give good arc starting properties, but the melting point exceeds 650℃ and the temperature exceeds 1750℃, which lowers the surface tension of molten iron. Metal elements that do not have any effect cannot provide extremely good arc starting properties. and a low melting point of 650°C or less and a boiling point of 17
A metal element that has a low boiling point of 50°C or less and lowers the surface tension of molten iron is 1% by weight based on the zero content in the wire.
If it is less than twice the 0 content, it will not be effective in reducing the surface tension of molten iron, and on the other hand, if it exceeds 20 times the 0 content by weight, arc stability will deteriorate and spatter will increase. , and cause hot embrittlement, so the content of the metal element that has a low melting point, low boiling point, and reduces the surface tension of molten iron should be 1% by weight, which is 2 to 20 times the 0 content. did. Next, the reason for limiting the range of components of the welding wire in a more preferred embodiment of the present invention will be explained. C: 0.15% by weight or less C is an element necessary to ensure the mechanical properties of the welded part. However, if it is contained in a large amount, it will impair the cracking resistance and cold workability of the welded part, so the content is limited to 0.15% by weight or less. Si: 0.3 to 2.4% by weight - Si is an effective component as a deoxidizing agent, and a minimum amount of 0.3% by weight is required. Further, although it is an element that is effective for arc stability and acid resistance, if it is contained in a large amount, the toughness in particular deteriorates, so it is limited to 2.4% by weight or less. And Si
A more desirable range of is 1.2 to 1.8% by weight. Mn: 0.4 to 2.0% by weight Mn is an element that acts as a deoxidizing agent and increases strength, and 0.4% by weight is necessary. However, if it is contained in a large amount, it will cause work hardening and deterioration of the bead shape.
The content was 2.0% by weight or less. A more desirable range of Mn is 0.4 to 0.8% by weight. 0: 0.002 to 0.04% by weight 0 is an effective component for increasing arc stability and lowering the surface tension of molten iron. The above is necessary. However, if it is contained in a large amount, it may cause blowholes and the like, so the content was set at 0.04% by weight or less. Bi, Sb, Pb: 0.0 in total of one type or two or more types
04 to 0.8% by weight Bi, Sb, and Pb are all metal elements that have a low melting point of 650° C. or lower and a low boiling point of 1750° C. or lower, and lower the surface tension of molten iron. And Bi affects the surface tension of pure iron. As seen in Figure 1, which shows the effects of Sb and Pb, O
Since the surface tension of molten iron begins to decrease at 0.004% by weight or more, which is more than twice the lower limit of 0.002% by weight, the content was set at 0.004% by weight or more. However, if the content exceeds 2θ times the upper limit of 0.04% by weight, the arc stability will deteriorate.
The upper limit of 0 content is 0.04% by weight, as this will lead to an increase in spatter generation and a pronounced hot brittleness.
20 times or less, that is, 0.8% by weight or less. In the welding wire according to the present invention, Bl. Figures 2, 3, and 4 show the results of investigating the effects of single addition of sb and pb on improving arc startability.As shown in Figure 2, Bi has the greatest improvement effect. This is followed by sb as shown in FIG. 3, and Pb as shown in FIG. However, pb alone is 0.8
It is not possible to obtain a 100% arc start rate even by weight percent. Therefore, it is more preferable to add Bi alone, but the objective can also be achieved by adding Bi in combination with sb and pb. The reason for this effect has not yet been fully elucidated, but low melting point and low boiling point metal elements lower the melting point of iron and lower the surface tension, thereby reducing the heat input during arc generation. It is presumed that this is due to the fact that the droplets become finer, the droplets become easier to separate from the wire, and the shape of the tip of the wire becomes sharper. (Function) The welding wire according to the present invention has a melting point of 650
0% by weight of metal elements that have a low melting point of 1750°C or less and a boiling point of 1750°C or less and reduce the surface tension of molten iron.
Since it contains 2 to 20 times the content,
This is a welding wire with extremely good arc starting properties. (Example) Table 1 shows the chemical composition of the solid wire for gas shielded arc welding used in the example of the present invention. , 6 to No. 1O are welding wires of the present invention. And No, 1-No, 10 shown in Table 1
Gas-shielded arc welding was performed using this welding wire, and arc startability in a downward position was evaluated. The gas shielded arc welding conditions at this time are welding current: 250
A, welding voltage: 25V, welding speed: 50cm/min,
Shield gas: 100% C02, shield gas flow rate: 2
01/min, stop for 15 seconds after welding 4 cm,
In a bead placement experiment in which 100 beads were placed at intervals of cm and welded an additional 4 cm, the arc start performance was evaluated by reading the number of sticks using a current-voltage oscilloscope. The results are shown in Table 2.
In the evaluation column of Table 2, ■ indicates that the arc startability was extremely good, 0 indicates that the arc startability was good, and Δ indicates that the arc startability was fair to good. , and X indicates that the arc startability was not good. Table 2 As is clear from the results shown in Table 2, No. The welding wires of the present invention with No. 6 to No. 10 are No. 1 to No. 1.
Compared to the conventional welding wire No. 5, the arc start rate has been significantly improved, and in particular, the welding wire No. 9 has a one-shot arc start rate of 100%, which is an ideal situation with no arc start failures. It was recognized that the system had achieved good results.

【Effect of the invention】

As is clear from the above description, the iron-based alloy welding wire according to the present invention has a low melting point of 650°C or less, a low boiling point of 1750°C or less, and reduces the surface tension of molten iron. 0 content of metal elements in weight% 2
Since it has a composition containing up to 20 times the content, the arc startability during arc welding using this welding wire can be made extremely good, and it greatly contributes to improving work efficiency and quality. This has the great effect of making it possible.

[Brief explanation of the drawing]

Figure 1 shows the effects of Bi and Sb on the surface tension of pure iron. Graphs showing the influence of Pb, Figures 2, 3, and 4 are graphs showing the influence of Bi content, Sb content, and Pb content on the one-shot arc start rate, respectively. Patent applicant: Daido Special Steel Co., Ltd.

Claims (3)

[Claims] (1) In the wire, a metal element having a low melting point of 650°C or less and a low boiling point of 1750°C or less and which lowers the surface tension of molten iron is contained in a weight percent of 2 to 20 times the O content. An iron-based alloy welding wire characterized by: (2) In weight%, C: 0.15% or less, Si: 0.3~
2.4%, Mn: 0.4-2.0%, O: 0.002-
0.04%, and a total of 0.004 to 0.8% of one or more selected from Bi, Sb, and Pb, with the remainder consisting of Fe and impurities. Base alloy welding wire. (3) In weight%, C: 0.15% or less, Si: 1.2~
1.8%, Mn: 0.4-0.8%, O: 0.002-
0.04%, and a total of 0.004 to 0.8% of one or more selected from Bi, Sb, and Pb, with the remainder consisting of Fe and impurities. Base alloy welding wire.