JPH0191973A - Welding method for titanium and titanium alloy - Google Patents

Abstract

PURPOSE:To perform welding with high welding strength without intercepting the air in inert gas or a vacuum by welding Ti or a Ti alloy by using a DC butt welding machine while applying the constant pressure on butt edges. CONSTITUTION:The Ti alloy is bent to form a cylindrical body 2 and its outside peripheral surface is held by arms 4 of a clamshell 3 and both the edges of abutment of the cylindrical body 2 are held by electrodes 5 of the DC butt welding machine. Next, the arms 4 of the clamshell 3 are moved in the arrow P directions and the welding is performed while applying the pressure on the abutment of both the edges. The pressing force, a current value, the displacement of a movable carriage and the heat input energy are controlled properly according to a kind of the alloy, a shape of material, etc. By this method, the welding with the high welding strength and satisfactory quality can be easily performed in the air without intercepting the air in the inert gas or the vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of welding titanium and titanium alloys.

[Conventional technology and its problems]

Titanium has excellent corrosion resistance, is light, and is strong, so its uses have expanded in recent years and the amount used has also increased.

The welding methods include TIG, MIG, plasma,
Resistance, seam, EB welding, etc. are used, but n2
T 1 a >8 tangent is often used.

However, titanium has a relatively high affinity with gases such as oxygen and reacts quickly, especially at high temperatures, so it easily absorbs these gases into the weld, resulting in significant hardening and
There are problems in that it causes embrittlement, reduces the ductility of the welded part, causes blowholes to occur in the weld metal, and deteriorates corrosion resistance.

Therefore, when welding titanium, it is necessary to completely shield the welding area from contamination by these gases by using inert gas or vacuum to block the atmosphere, and to thoroughly clean the welding materials and working environment. However, this requires extra equipment and labor, has poor productivity, increases manufacturing costs, and has the problem of degrading quality when impure gas is mixed in.

FIG. 4 shows the hardness of a welded part of titanium welded by mixing an impure gas into argon, which is an inert gas. As described above, the presence of a very small amount of impurity gas in the argon gas significantly increases the hardness of the weld and reduces the toughness.

[Means for solving problems]

The present invention has been made to solve the above problems, and is characterized by gripping each of the butt ends with an electrode of a DC butt welding machine, and welding the ends together while applying pressure. The present invention provides a method for welding titanium and titanium alloys in the atmosphere without degrading quality.

[Effect]

In the present invention, by using a direct current type butt welding machine, heat is first applied to the abutting end surfaces of titanium or titanium alloy. Then, as the abutting end faces oxidize and melt, the titanium or titanium alloy is pressed against each other, pushing out the oxidized metal, resulting in a healthy metal bond between the titanium or titanium alloy at the welding interface.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIGS. 1(A) and (I7), when forming a cylindrical material for the rim of a titanium alloy wheel, a titanium alloy plate 1 is curved to form a cylindrical body 2, and the outer circumference of the cylindrical body 2 is The surface is held by the arm 4 of the clamshell 3 as shown in FIG. 2, and both abutting ends of the cylindrical body 2 are held by the electrodes 5 of a DC type hat welding machine.

Next, while holding both ends of the cylindrical body 2 with the electrodes 5, move the arm 4 of the clamshell 3 in the direction of arrow P, and apply 10 kg/w2 to the abutting portions of both ends without applying voltage to the electrodes 5. Squeeze for 20 Hz while applying pressure. Then, while maintaining the above pressure, a current of 50 A/2 times is applied to the electrode 5, and this current is gradually increased to 55 A/2 times for 15 Hz to perform an upslope. Furthermore, increase this current to 60A/n+m2, and this N,
Welding is carried out at 20 Hz while increasing the current to 20 Hz, and when welding is completed, the current is lowered and held for 20 Hz to complete welding (Figure 3).

The above welding conditions are just an example, and good welding can be achieved by appropriately controlling the pressure, current value, displacement of the moving table, and heat input energy depending on the type of alloy, shape of the material, etc. Yes, in the above example, the pressing force was 10k.
g/mm2, but a range of 5 to 15 kg 7 mm2 is appropriate; 5) If it is less than cg/mm', the oxidized metal and impurity gas generated on the welding surface will not be pushed out, and a sound metal bond will not be formed. However, if the weight exceeds 15 kg/am2, normal weld metal will be pushed out, resulting in material loss.

Sixth, the ranges shown in Tables 1 and 2 are appropriate for the welding elapsed time and secondary current value.

Table 1: Elapsed welding time Table 2: Secondary current value [Effects of the invention] As described above, the present invention uses a direct current type butt welder to weld titanium or titanium alloy while applying constant pressure. It becomes possible to easily perform high-quality welding with high welding strength in the atmosphere without blocking the atmosphere with gas or vacuum.

Moreover, it does not require complicated equipment, and has excellent effects in that productivity can be greatly improved and costs can be reduced.

[Brief explanation of the drawing]

Figure 1 (a) is a perspective view of a titanium alloy plate used in the δ welding method of the present invention, (b) is a perspective view of (a) formed into a cylindrical shape, and Figure 2 is a perspective view of a titanium alloy plate used in the welding method of the present invention. A schematic explanatory diagram showing one embodiment of a butting device, FIG. 3 is a curve diagram showing one embodiment of the welding pattern of the present invention, and FIG. 4 is a curve diagram showing the hardness of 78 joints by a conventional welding method. be. 1... Titanium alloy plate 2... Cylindrical body 3... Clamshell 4... Arm 5... Electrode No. 1121 (4) ( ' Figure 2

Claims (1)

[Claims] A method for welding titanium and titanium alloys, in which each of the butted ends is gripped with an electrode of a DC butt welder, and the ends are butted and welded while applying pressure.