JPS5982187A - Strengthening method of deposited metal - Google Patents

Abstract

PURPOSE:To strengthen the deposited metal at the final pass that requires aging or tempering by irradiating an arc or the like to the deposited metal corresponding to the final pass in the stage of welding thereby heating the same to the m.p. thereof or below. CONSTITUTION:If deposited metals 1-10 are welded on a base material O by performing ten passes of welding, the effect of tempering or aging is obtd. by the welding heat of 2-10 passes respectively in the intermediate pass corresponding to 1-9 passes, but said effect is not obtd. in the 10th pass. Therefore an irradiation by an arc, electron beam, laser light or plasma is applied to the deposited metal 10 corresponding to the final pass in the stage of welding to heat said metal to the m.p. thereof or below, thereby strengthening the metal 10. The irradiation of laser light is preferably applied in the atmospheric air, the electron beam in a vacuum and the plasma and arc in an inert gaseous atmosphere.

Description

[Detailed description of the invention] Concerning transformation.

When manufacturing pressure shells used at ultra-high pressures such as 20001Tl deep-sea submersible research vessels or 6000m deep-sea submersible research vessels,
There are cases where it is necessary to perform inset welding of penetrating metal fittings to the ultra-high tensile steel that constitutes these pressure-resistant shells. These welded joints do not allow thickening or cutting after welding, and the appearance quality is also strict.

The specified strength (02%) is achieved by welding with the normal number of passes.
It is required to obtain yield strength and gokgr/m+fi).

These welding methods are generally covered arc welding or T
IG welding method etc. are used. Multilayer build-up welding as shown in FIG. 1 is often performed using plate J1.

In Fig. 451, 0 indicates the welding hole and 1 to 10 indicate the weld metal, and each number corresponds to a welding pass.

If the abrasive material is used after quenching and then tempering or aging, in the case of 10-pass welding as shown in Figure 1, the intermediate passes corresponding to 1 to 9 baths are The effect of tempering or aging is obtained by the welding heat of ~10 passes, and the strength level of IW, which is the same as that of steel that has been quenched and tempered or quenched and aged, is obtained. However, this effect cannot be obtained in the final pass of 10 passes, and the heat generated by strong electric current is reduced to that of steel that has only been quenched. For example, Nx80, Ny+90, lONi-8C
! o steel, etc. 02%1 control force is 80~140 kg r
/mm class high tensile strength steel, the 0 of the deposited metal on the 10th pass
．． The 2% proof stress is lowered by about IO~20 kgf/111 m1 compared to the 02% proof stress of other weld metals.

For this reason, conventionally in actual welded joints.

(1) Considering the decrease in strength of the final pass, thicken the plate thickness of the joint part in advance ■ In addition to the number of passes to achieve the normal reinforcement shape, add extra layers to increase the part with a high 1-strength level. However, even with these countermeasures, the shape of the joint after welding becomes rough and uneven, resulting in
There are also cases where it is necessary to cut the thickened part or the excess part.

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art and to provide a method for strengthening welded metal in the final pass portion without increasing the extra plate thickness or increasing the extra layer.

For this reason, the method for strengthening weld metal according to the present invention is to irradiate the weld metal with arc, electric beam, laser light, or plasma [1 ((( The gist is heating.

Note that the laser beam is in the atmosphere, and the electronic heat is 1 in a vacuum.
Plasma and arcing are often performed in an inert gas atmosphere. Also, irradiation of welded metal with arc, etc.
In both cases, it is necessary to irradiate the welded metal corresponding to the final busbar, which is the case with CJ, and other welded metals may also be irradiated.

Arc, electric beam, laser beam, and plasma all have a high inertness density, but for example, in stingrays, gas moxibustion, etc. with a low inertness density, heat diffusion is large and the temperature rise is insufficient. Since no improvement in 02% yield strength could be expected, it was limited as described in 114.

In addition, the alloy targeted by the present invention is not limited to the ultra-high tensile steel shown in this example, but also A+ gold alloy copper alloy,
All metal abrasives used for immediate heat treatment such as alloys such as 'I'1 alloy are included, but the effect of +lf% Jq abrasive A'1 is remarkable.

EXAMPLES Hereinafter, the method of converting weld metal into 4i according to the present invention will be explained using Examples.

As a practical example, we will explain the welding strength test results assuming the pressure hull of a 2000m deep-sea research submersible.

Figure Is 2 shows a schematic cross-sectional view of the groove shape of the joint welded in this example. In Fig. 2, (a) is a through fitting fitting joint (■ (bevel) is the plate thickness (t) a Omm
, (b), the equatorial joint (U groove) has a plate thickness (t 140 mm, and the two joints table is also Ul) last month (φ) 12°, and groove radius (It) 6 mm.

The matrix has a composition shown in Table 1 with a yield strength of 90 kgf/m.
- Lehel quenched and tempered steel N590 was used, and the wire corresponding to the weld metal was a round, downward automatic 1' IQ weld of hemlock thread TN8 having the composition shown in Table 2.

The welding conditions are as shown in Table 8.

- That is, after completing the 6th pass, which is the final pass.

Stopping the feeding of the welding wire and irradiating the arc twice onto the welded metal while allowing the arc current to increase slightly. Here, the current value at the irradiation path port is 200 to 800 A,
! ! (It is preferable that the current value of the second irradiation pass is 150 to 25 OA, and the current value of the lower irradiation pass is 200.A or less in terms of heat treatment effect and O/workability.

Figure 3 (+) for test H using welding and the method of the present invention.
JI with a diameter of 6 mm at 1+ from the location shown in , +1])
A No. 87°8111 A-2 tensile test piece was taken and subjected to a tensile test. The results are shown in Table 4. Furthermore, Figure 3 (
In al, (b), the test piece of the surface layer A is taken Jle
Collect a test piece from the central part B of the 11° plate with a thickness of 1 corner +
2 is 4mm and 7.5mm respectively.
mm, and one surface layer (J specimen collection (3/,
i# t3. Testing of the center part of plate J7

As shown in the results in Table 4, in the R/R conventional joint that is arranged in the second surface layer and is not heated by an arc, the 02% yield strength of the central part B and D of the plate thickness is 98 to 100 kgr/-. Although the value is high, 1st surface layer A and C have 9 kgr/
mnl #80-85kgf/mnl, which is also below the target value
Only 02% yield strength with low culm degree can be obtained. In the central part of the cap 1'f', the welded metal in each pass is thermally affected by the welded metal in the pass θ() and is annealed, resulting in a high yield strength, but the welded metal in the final pass is Since it is not tempered, its yield strength remains low.

In line with this, in the joint of the present invention in which the surface layer is irradiated with an arc, even in Table 11 η parts A and C, the weight is 98 to 100 kgf.
/m-, it has a high yield strength equivalent to that of plate J7 middle part T3 and J). 2. In this embodiment, after welding, the same welding equipment can be used as is, and heating can be carried out by simply stopping the wire feed and lowering the arc's current, so no special equipment or special preparatory work is required. Moreover, there is an advantage that the work can be done easily and quickly. Furthermore, since there is no need to feed four rough wires for heat treatment, the heat shape does not rise unnaturally, and there is no need to cut the excess portion.

As described above, according to the strengthening method of the present invention, it is possible to strengthen the weld metal in a phase that requires aging or tempering using a heating element with a high energy density, and the shape of the joint after welding can be changed. It is made uniform, and there is no need to cut the excess portion.

Therefore, the method of the present invention can be applied to all welded parts of feed that undergo 1-1 tempering or 11-r effect after quenching, but it is especially suitable for deep-diving research vessels with severe processing accuracy requirements. It is suitable as a method for strengthening the welding joints of 2m-beam penstocks in the pressure shells of submarines, etc.

Table 3 Welding conditions

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view of a welded joint, Fig. 2 is a schematic cross-sectional view of a welded joint for explaining the groove shape, Fig. 3 is a schematic cross-sectional view of a welded joint for explaining the specimen sampling position, and (a) is a schematic cross-sectional view of the welded joint for explaining the groove shape. Form development, 0
]) indicates a U-shaped groove. 0...Material phase, 1-10.Weld metal

Claims (1)

[Claims] Arc, electron beam l1. A method of strengthening weld metal characterized by irradiating laser light or plasma to heat it to a temperature below its melting point.