JPS58187298A - Steel wire for arc welding - Google Patents

Abstract

PURPOSE:To reduce generation of spatter, by specifying the total oxygen quantity of a wire consisting of steel containing C, Si, Mn and Ti of each specified rate, and using it for carbonic acid gas shielded arc welding in a globular transfer area. CONSTITUTION:The total oxygen quantity of a wire 1 consisting of steel which contains 0.06-0.15% C, 0.50-1.20% Si, 0.90-1.90% Mn and 0.10-0.35% Ti in wt%, and balance Fe and inevitable impurities as the remainder is prescribed to 100-500ppm. As for a transferring form of a molten metal 2 under a large current in case of carbonic acid gas arc welding, the molten metal 2 is formed at the tip of the wire 1, and it is detached and transferred to a base metal 3 and a molten pool 4. In this case, a shape of the molten metal 2 of the tip of the wire 1 is globular, and an arc generating face 6 is dispersed to its lower face and an arc is generated. Therefore, the molten metal 2 scarcely causes such a phenomenon as pushed back by pressure of the arc, a smooth globular transfer phenomenon is generated, and spatter is reduced to half.

Description

[Detailed description of the invention] This invention relates to steel wire for carbon dioxide arc welding that is excellent in carbon dioxide gas arc welding.

Generally, the steel wire used for carbon dioxide arc bath welding has a wire diameter of 0.8 to 2.0 mm. It is a 4 m long hoko, usually plated with steel, and is supplied wound around a spool or bobbin, or loaded into a cylindrical container called a pail pack. All of these are set in a wire feeder, which is an accessory to a welding machine, and are used for automatic or semi-automatic bath welding.

~ Carbon dioxide arc welding has lower efficiency and control efficiency compared to other welding methods.
It has the characteristics of high tube quality and low cost, and recently there has been a growing trend to take advantage of these characteristics to make welding automatic, more complex, and more advanced, and to expand the scope of application of carbon dioxide gas arc welding and welding.

However, although this carbon dioxide gas arc welding has the above-mentioned features, a major drawback is that wire bath molten droplets called spatter are frequently scattered during bath welding, and the workability of bath welding is poor. This occurrence of spatter is noticeable under welding conditions in which the wire transfers in the form of droplets, usually in a large current range of about 230 A or more.

The generation of spatter reduces wire welding efficiency and reduces efficiency. Furthermore, protection against spatter must be provided during bath contact, which makes bath contact work difficult. The generated spatter adheres to the nozzle and obstructs the carbon dioxide shield, impairing the welding result. In addition, the spatter adheres to the vicinity of the weld, spoiling the appearance of the welded product, and requires labor to remove the adhering spatter, which has been a major problem with the carbon dioxide bath welding method in a large current range.

The following measures have been taken in the prior art as measures to reduce spatter under the bath welding conditions in the high current droplet transfer region of the carbon dioxide arc bath welding method, but these measures are still unsatisfactory as will be described later.

■) Improving power supply characteristics 2) Adjusting welding conditions 3) Mixing Ar gas with shield 9 gas 4) Adding alloying elements to wire 1) Improved rectification method, power output characteristics, and wire supply control method of carbon dioxide arc welding machine The aim is to improve this and reduce the occurrence of spatter. However, the occurrence of spatter is related to the carbon dioxide arc bath contact phenomenon. Therefore, there is a limit to reducing spatter only from the sides of a few bath equipment.2) Depending on the bath contact position and the form of the workpiece, welding conditions (wire diameter, welding current, arc voltage, wire diameter, welding current, arc voltage, This is to adjust the protruding length of the wire, the angle and moving speed of the welding torch, etc. This also had limitations because the welding conditions were determined based on factors such as bathing, bead shape, and the soundness of the welded part, rather than with the primary focus on preventing spatter.

3) The shield 9 gas is changed from carbon dioxide to a gas mainly composed of Ar, which is an inert gas (for example, Ar gas 8°, CO2
20% gas) to reduce the generation of ivy. This method creates an arc phenomenon in a gas mainly composed of Ar, stabilizes the arc, and reduces the occurrence of spatter, and is an effective method. However, this method loses the cost advantage of using very cheap carbon dioxide gas.

4) is to prevent the occurrence of spatter by adding an alloying element to the wire, and the effect of adding titanium is known, as disclosed in Japanese Patent Publication No. 3256 of 1970. Also JIS
Z3312 is standardized as Ycw-1 and is widely used. However, as mentioned above, the conventional wire has the problem of spatter generation.

As detailed above, in order to reduce spatter generation under welding conditions under the high current droplet transfer region of carbon dioxide arc welding,
There were problems with the conventional technology, and a new technology was needed.

In view of the current situation where it is difficult to reduce the occurrence of spatter using conventional techniques, the inventors of the present invention have solved the problem using a novel method of adjusting the total amount of oxygen in the steel wire and changing the carbon dioxide arc welding phenomenon.

That is, the gist of the present invention is to adjust the total oxygen content of the wire to 100 to 500 ppm K in a copper wire for carbon dioxide gas welding used in a high current droplet transfer region, and to
．． 06-0.15% (wt%), Si0.5-1.2%
, Mn 0.90~1.90% and Ti 0.10~
0.35% with the remainder being substantially Fe in the droplet transfer region to reduce spatter generation.

The greatest feature of the wire of the present invention is that the oxygen and oxides contained in the wire are positively and effectively utilized to change the arc phenomenon.

Conventional wires were usually subjected to sufficient deoxidation treatment during steel manufacturing to reduce oxygen in the steel. Furthermore, in the production of steel wire, it has been customary to perform sufficient pre-plating treatment to improve the adhesion between the copper plating and the steel base. In addition, even when heat treatment is performed after steel plating to oxidize the copper, pickling treatment or the like is performed to remove the grade oxide.

As a result, the total acid content of the steel wire was less than 100 ppm, and there was no technical idea to intentionally adjust or regulate the total oxygen amount to 100 to 500 ppm.

The total amount of oxygen referred to here is the result of extracting and analyzing oxygen and oxides in the steel of the steel wire, between the copper plating and the steel base, in the copper plating layer, and on the surface.

The following describes the phenomenon in which the adjustment of the total oxygen content (100 to 5001) pm caused a surprising change in arc generation.

This article describes the observation results regarding the relationship between carbon dioxide bath arc phenomenon and spatter generation when conventional wires are used.

The transfer of bath molten metal under large current in carbon dioxide arc welding is performed by forming bath molten metal at the tip of the wire due to arc heat, separating it, and transferring it to the base metal and molten pool. At this time, the arc generated between the wire and the base material is strongly focused in the anode region (hereinafter referred to as the arc leg) under ml of the wire molten metal, as a characteristic of the carbon dioxide arc, which is a diatomic molecule. The wire molten metal is pushed up by this reaction force (arc force) on the arc generation surface, and at the same time, the arc always moves to the closest location to the base metal and molten pool.

As a result, the shape of the molten metal produced at the tip of the wire is irregular and moves violently. Eventually, it separates from the wire end, becomes a droplet, and transfers to the base material/molten pool, that is, it transfers to a droplet. Furthermore, as a result of the intense arc force, the molten metal at the wire end sometimes causes an instantaneous short circuit with the base metal and the molten pool, causing an explosive re-arc (at which point the arc is extinguished).

It has been found that the spatter generation process is due to the focusing and movement of the anode region or arc legs and explosive re-arcing phenomena, especially from momentary short circuits (less than 0.01 seconds).

The inventor of the present invention discovered that the occurrence of spatter under conditions of high current interparticle transfer bath contact is mainly due to the arc force of an explosive short-circuit when an instantaneous short circuit of 0.01 seconds or less is broken. Many experiments were conducted regarding wire composition and spatter generation.

As a result, when the total oxygen content of the steel wire is adjusted to 100 to 500 ppm and the alloying elements are included in the above content range, unlike conventional wires, the generation of s. A steel wire with excellent workability was obtained with little bath welding. The total amount of oxygen in the steel wire is 100-500 pp.
The reason for restricting it to m will be described later, but first we will discuss the differences between the wire of the present invention and the conventional wire regarding the bath welding arc phenomenon.

FIGS. 1(a) and 1(b) are modeled comparisons of arc phenomena and droplet transfer between a conventional wire and a wire according to the present invention.

1 is a wire for arc bath welding, 2 is metal melted by the heat of the arc 5, and 2 is a base material to be welded. From the bath molten metal 2, an arc with the base metal 1 is maintained with the surface closest to the base metal 3 or molten pool 4 serving as the arc generation surface 6.

The conventional wire is in an extremely unstable state as shown in FIG. 1(a), but the example of the wire of the present invention (as shown in FIG. 1(b)
As shown in FIG. 1, the shape of the molten metal 2 at the tip of the wire 1 is spherical, and the arc generating surface 6 is distributed and generated on the lower surface thereof. The molten metal 2 at the tip of the wire 1 was hardly pushed back by the pressure of the car and arc, which grow sequentially, and a smooth droplet transfer phenomenon occurred. The instantaneous shortening phenomenon was reduced to about 1/2 or less compared to conventional wire. And the occurrence of spatter was halved.

It is not clear why the total amount of oxygen in the wire causes such a change in the arc phenomenon, but the total amount of oxygen is expressed as extracted oxygen, but there are Oxygen and oxides on the plating surface are carried to the end of the wire where the arc occurs, enveloping the surface of the droplet and lowering the surface tension of the droplet. It is presumed that the discharge phenomenon has been changed.

These oxygen and oxides form a state in which the end of the wire and the entire surface of the molten metal are covered, and the total amount of oxygen is 100 pp.
It is considered that the time is more than m.

FIG. 2 shows the relationship between the total amount of oxygen in the wire and the number of instantaneous short circuits. The number of instantaneous short circuits was obtained by recording and analyzing the bath contact current and arc voltage during welding, and the wires and welding conditions used are shown in Table 1 and are the same as in FIG. 3, which will be described later. The momentary short circuit phenomenon occurs when the total amount of oxygen in the wire is 100 p.
When it exceeded pm, it suddenly decreased, and when it exceeded 500 ppm, the results were rather variable. This result would indicate that excessive total oxygen content is detrimental to reducing spatter.

Next, the reason for setting the limited ranges for each of the alloying elements C1Si, M11, and Ti will be described.

When C is less than 0.06%, the total amount of spatter does not change, but large spatter particles occur.

Large grains of spatter and ξ ivy adhere firmly to the nozzle and the vicinity of welding parts, causing spatter removal problems frequently.

Therefore, the C content was set to 0.06% or more. 006%C
Under the above conditions, the droplet transfer was smooth and the number of squirrel locusts decreased slightly. This appears to be the result of active CO reactions in the droplets and molten pool in the carbon dioxide arc.

However, if the C content of the wire exceeds 0.15%, the C content of the weld metal will increase, resulting in high tensile strength, decreased elongation, and a decrease in impact toughness. Limited.

Carbon dioxide arc welding wire contains Si and Mn during welding.
It is necessary to add it in consideration of its consumption.

Moreover, since droplet transfer welding is performed under high current and tube arc voltage, there is a significant tendency for Sl r IVfn to be consumed. St 7! l″-0, less than 50%, seed 0.
When it was less than 90%, as with C, large spatters were generated, Si and Mn in the weld metal decreased, and weld beads, pores, and pits were generated.

When Si is 0.50% or more and Seed is 0.90% or more, large spatter does not occur.
If the Sis of the weld metal exceeds 1.90% and the ground content exceeds 1.90%,
The Mn content increased, hardening occurred, elongation decreased, and impact toughness decreased. Therefore, the appropriate range is Si 0.50
-1.20%,] Vfn was limited to 0.90-1.90%.

Next, we will talk about the effects of Ti. As mentioned above, adding Ti to the wire is effective in reducing ivy. However, Ti spatter reduction was found to have a significant effect when adjusting the total oxygen content of the wire. It is assumed that this is not because the Ti in the wire reduces spatter, but because Ti exists as an oxide of TiO2 on the surface of the droplet and changes the surface tension and arc discharge phenomenon.

Figure 4 shows the relationship between the amount of Ti added to the wire, the total amount of oxygen, and the occurrence of sputtering.
It can be seen that the wire of the present invention having a Ti content of 0.10% or more significantly reduces spatter compared to the conventional wire having a total oxygen content of 80 ppm. Note that the welding conditions in FIG. 4 are the same as in Table 1, which will be described later. Furthermore, by adjusting the total amount of oxygen, the slag is removed as TiO2 by reaction during bath welding, so the yield of wire wire Ti to bath weld metal is lower than that of conventional wire.

However, if the Ti content of the wire exceeds 03'5%, the yield of Ti in the bath metal will increase, and as a result of the strong acidity of Ti, the yields of Si and Mn will also increase at the same time. As a result, the mechanical properties of the weld metal were significantly deteriorated, such as hardening, decreased elongation, and decreased impact value.

Therefore, the appropriate Ti range was set to 0.10 to 0.35 Ti.

FIG. 3 is an example showing the relationship between the total amount of oxygen in the wire and the occurrence of spatter. Total oxygen content of wire 100-500
It can be seen that spatter is reduced by ppm. The welding steel wire and welding conditions at this time were those shown in Table 1, and downward bead welding was performed in a spatter collection box.

Table 1 The total oxygen content of the welding steel wire was adjusted by heat-treating the copper-plated wire in an atmospheric gas with a regulated oxygen gas partial pressure.

As shown in Figure 3, the total oxygen content of the wire is 100-500.
By adjusting the ppm, the amount of spatter generated is reduced by about half compared to conventional wires with less than 100 ppm.

In addition to the oxidation treatment of copper plating, adjustment of the total oxygen acid also achieved the same spatter reduction effect by using oxygen and oxides in the steel, or by oxygen and hydrides under copper plating.

Steel wire 1 for carbon dioxide arc welding is JISZ 33
There are wires for mild steel, high-strength steel other than 50 kg class high-tensile steel, heat-resistant steel, low-temperature steel, and weather-resistant steel that are standardized to 12, and these wires are used for high-current droplet transfer welding. used in conditions. These wires contain Cu % NiN C as an alloying element to suit each of the above applications.
r N Mo, corner, and ■, or any combination of two or more thereof, and a specified acid is added. Regarding steel wires for these various uses, the total oxygen content is 100 to 500 p.
By adjusting the content of C, Si, Mn, and Ti to within the range of the present invention, the occurrence of spatter can be reduced, and the present invention can be applied and exert its effects.

The effects of the present invention are summarized as follows.

1) Spatter occurring frequently under droplet transfer bath conditions in carbon dioxide arc bath welding was reduced to less than 1/2. As a result, we were able to increase wire welding efficiency and bath welding efficiency.

2) Reducing the generation of ivy improves the tendency for spatter to adhere to the nozzle, deteriorate the gas shield, and impair the bath welding results.

3) Reduced damage to the appearance of the welded object due to spatter generation, and reduced the labor required to remove it.

4) The welding arc phenomenon changed to a favorable arc phenomenon with less spatter generation, and bath welding workability was improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram comparing the arc phenomenon and droplet transfer between conventional wire and wire of the present invention, Fig. 2 is a diagram showing the relationship between the total oxygen content of the wire and the number of instantaneous short circuits, and Fig. 3 is the total FIG. 4 is a chart showing the relationship between the amount of oxygen and the amount of spatter generated. FIG. 4 is a chart showing the relationship between the amount of Ti in the wire and the amount of spatter generated. 7sa) 5 no t? ■ (α) (b)

Claims (1)

[Claims] The total oxygen content of the wire is 100 to 500 ppm, and C
:006~0.15 section (same below weight section), SiO, 5
0-120%, Seed; 090-1.90%, Ti:O, 1
0 to 035%, and the remainder is t+'e
A steel wire for arc bath welding, which is characterized by low spatter generation when used in carbon dioxide shielded arc bath welding with droplet migration head.