JPS5829580A - Shielding or restraining gaseous mixture - Google Patents

Abstract

PURPOSE:To improve productivity without degrating the mechanical properties of melt stuck parts by using a gaseous mixture consisting of specific mixing ratios of gaseous hydrogen and gaseous argon as a shielding or restarting gaseous mixture. CONSTITUTION:A gaseous mixture of 0.5-3.5% gaseous hydrogen and the balance gaseous argon is used for an shielding or restraining gaseous mixing for inert gas shielded tungsten welding or plasma welding for both automatic and manual welding. If the thickness of welding materials is <=3.2mm., the gaseous mixture mixed with the gaseous hydrogen at the rate of the numerical value approximately equal to the numerical value of the thickness is used, whereby the speed of welding procedures is increased without degrading the mechanical properties of deposited parts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a mixture of argon gas and hydrogen gas used for automatic and manual inert gas encapsulated tungsten welding (TIG) or plasma welding. Regarding gas.

Argon gas is most often used as the encapsulating gas in welding ordinary steel, stainless steel, or low alloy steel.

The reason why argon gas is frequently used is that it responds to changes in the arc length and welding current setting range during welding, and its effect on welding results is slow (1 to 1), and the degree to which it is affected by differences in the skill of welding workers. It is known that this is due to the small size of

On the other hand, instead of argon gas, an encapsulating gas such as heliuno gas, a mixed gas of argon gas and 60 to 80% helium gas, or a mixed gas of argon gas and 5 to 65% hydrogen gas may be used. Used for welding or plasma welding.

Helium gas-rich encapsulation gas as described above and 5 to 35
In the case of an encapsulated gas with a mixed composition of dihydrogen gas and argon gas, it is difficult to start the arc unless the welding machine's electric detection: high pressure is used, and the weld penetration of the weld metal is large. It is known that when welding thin plates to be welded, welding often occurs more frequently. Therefore, the thickness of the material to be welded is 2.3+n+o or more, or the use is limited to encapsulating gas for high-speed automatic TIG welding, where there are few factors that change the setting of welding conditions, and restraining gas for plasma welding and plasma cutting. From the above-mentioned viewpoint, the present inventor has succeeded in developing the present invention as a result of glaze inspection and experiments, and the gist of the present invention is the above-mentioned patent claim. This is clearly stated in the scope of the invention.
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The encapsulated or restrained mixed gas of the present invention is a mixture of 0.5 to 6.5 liters of hydrogen gas and the balance argon gas.
However, if the thickness of the material to be welded is 3-2 nun or less, Kr
It was found from Findings 1 to 1 that by using a mixed gas with a hydrogen gas mixing ratio that is approximately the same as the value of the plate thickness, the welding speed can be improved without reducing the mechanical properties of the welded part.

Tables 1 (TIG welding) and p2 (f plasma welding) show welding conditions and welding results when argon is used as the encapsulating gas (or restraining gas) and when the argon + hydrogen mixed gas of the present invention is used. In these experiments, the materials to be welded were ferritic and austenitic steels.

(11) The potential gradient of the encapsulated gas of the present invention is close to that of Ar, so that a conventional Arif gas welding machine can be used without modification, and the arc can be started easily.

(2) Capable of manual and automatic 1" IC welding and manual plasma welding of stainless steel, common steel, and low-alloy steel with plate thicknesses of 0.41 mm or more. The welding speed for manual welding varies depending on the technology, but generally 1" ~50L: 1 n/min, and since automatic welding has few factors to change the settings of welding conditions, it can be set arbitrarily.

Compared to +3+ Ar gas, an increase in welding speed of 15-4 Gt at the same welding current value can be achieved with excellent joint mechanical performance, appearance, and under-wave formation.

(4) Compared to austenitic steel materials, it is known that in ferritic steel materials, the crystals in the weld zone become coarser due to an increase in welding heat input, which significantly reduces the mechanical performance of the weld zone. When the mixed gas of the present invention is used as the encapsulating gas, even ferritic welding materials, which are difficult to weld, have stable mechanical properties as shown in Tables 6 and 4.
It has been found that the distortion of the welded product can be reduced as well as the welding speed improved.

Table 1 and Table 3 show an example comparing the welding speeds when the mixed gas of the present invention and Ar gas are used as the encapsulating gas and 17, respectively, in TIG welding of ferritic steel, and Table 4 shows the welding speed of TIG welding of ferritic steel. This table shows a comparison of the bead "1" and its mechanical performance under the respective welding conditions shown in Table 6 when the mixed gas of the present invention and Ar gas are used as encapsulating gases in TIG welding.

Generally, in thin plate welding, in order to obtain the mechanical strength of the welded part, that is, the joint part, close to the strength of the material to be welded, the bead width of the back wave (back bead width) should be set to 1 to 1.5 times the thickness of the material to be welded. Must be managed within a range. Even when the front bead width is set approximately constant, the penetration index (front bead [IJ/back bead width)] is Ar.
In the case of gas, it is around 2 and there is some variation, whereas in the case of the mixed gas of the present invention, it is around 1.5 and can be improved with less variation. When the actual welded product is cylindrical or box-shaped, not only thin plates, it is often impossible to visually see the inner corrugation and the width of the bead formed on the inside.

In addition, when using an encapsulating gas with a large penetration index such as Ar gas, the wetting properties are high even if it falls on a thin plate, and the front bead width becomes wider, but on the other hand, it is difficult to generate back waves, and there is a large variation in the surface bead width. It is difficult to manage the back bead depending on the bead width. 1 to 1, the mixed gas of the present invention has less sluggishness in the melt penetration index, and the width of the back bead by the front bead 11 can be easily controlled and productivity can be improved.

Alloyed silver can be used without hydrogen embrittlement and welding defects.

(In 617°72" ma welding, the same type of gas as the restraining gas can be used as the plasma gas (pilot arc gas), which increases the construction speed and improves the quality of the welded product.

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Claims (1)

[Claims] A encapsulated or constrained mixed gas consisting of D.5 to 6.5% hydrogen gas and the balance argon gas for automatic and manual inert gas encapsulated tungsten welding or plasma welding.