JPS58168495A - Welding method of clad steel - Google Patents

Abstract

PURPOSE:To weld a clad steel with a joint having good durability to thermal stress by removing cladding material partly, butt welding the same, attaching a waste plate through an intermediate layer of silver or the like by resistance welding onto said materials and welding a strap plate thereon. CONSTITUTION:The cladding materials 11a, 11b of clad steels produced with cladding materials 11a, 11b of Ti or Zr on carbon steels 10a, 10b are removed respectively by l1 width and are butt welded 12. A thin intermediate sheet material 13 of silver or a silver alloy having weldability to both of carbon steel and Ti, etc. and a waste plate of the same material as the material 11a, etc. are disposed in the exposed parts of the carbon steels, and the plate 15 is attached to the materials 11a, 11b by butt welding 19 and the plate 15, the material 13 and the steels 10a, 10b are resistance welded 18 by moving electrodes P, P'. A strap plate 16 which is of the same material as the material of the plate 15 and is broader than the same is disposed and is fillet welded 20 to the materials 11a, 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding method for clad steel in which carbon steel is clad with a cladding material consisting of a single bridge of titanium or zirconium, which has particularly good durability against thermal stress and is reliable. The present invention relates to a welding method for obtaining joints with high properties.

What is shown in 1tXJ is a conventional joint structure of clad steel clad with cladding material made of one type of titanium or zirconium. 4), and the cluttering material (21) and (
2b) is partially cut out, and a sacrificial plate (3) made of the same material as the cladding material inserted into this cut portion is butt-welded to the cladding material (2b) and (2b) at both ends. The cladding material and porcelain backing plate (8) that has been F51 and placed over the above-mentioned excised portion are:
Cladding material (2 friends) at both ends, (2b)
Fillet welds (71, +71) are applied.

In this way, base metals are welded together with base metals, and cladding materials are welded together with tarawading materials through a backing plate of the same material.The reason why titanium, etc. has to be welded with carbon IAJII is that they must be welded separately. This is because it cannot be done.

However, titanium and zirconium have lower coefficients of thermal expansion than carbon steel, and in a structure where the cladding material side and the base metal side are not integral at the clattering material cutaway part as described above, the reaction chamber 1, the heat exchanger When operating at high temperatures, such as in a single reactor, or during batch operation, where the temperature is repeatedly raised and lowered, cracks often occur in the patch plate hot junction (7). Moreover, the welded part of the waste plate (3) (
5) has low strength because it can only be welded to a depth of about half the thickness of the scrap plate to prevent the penetration from penetrating into the carbon end, and the thermal expansion between the scrap plate and the base metal is low! This weld part bears most of the stress caused by the welding, and has a shape that does not concentrate stress, so if a crack occurs at the hot welding part (7) of the patch plate as described above, the welding part will be removed from the welded part. In many cases, cracks have already occurred in (5), and there is a drawback that corrosive liquid infiltrates the base material surface, causing corrosion of the base material.

In addition, even if the Test Vibe +a+, which detects corrosive liquid that has penetrated, is inserted between the caul plate (6) and the cladding material (21) as shown in the figure, the hot junction of the caul plate (7)
If cracks occur in the waste plate welded portion (5) prior to cracking, the early detection method of corrosion using the test pipe described above cannot be expected to be very effective.

These disadvantages are, in short, in the conventional joint structure, there is no integrity between the waste plate and the carbon steel base material in contact with it, and the difference in thermal expansion between the carbon steel base material and the waste plate in this part (2z,) This is due to the tensile force being concentrated on the welded parts (5) and (7). 7 The present invention is directed to heat I
This provides a welding method for forming a joint structure that can absorb the tension difference.The gist of the welding method is to cut out a part of the cladding material, form a groove that exposes the carbon steel surface, and then butt the joint structure. Welding, then placing an intermediate material made of silver or silver alloy on the exposed part of the carbon steel surface, and further placing a waste plate made of the same material as the cladding material on the intermediate material, and then combining the waste plate and the cladding material. At the same time as welding the butt parts of
Weld the waste plate, intermediate material and carbon steel by resistance welding,
This is a welding method for clad steel in which a backing plate made of the same material as the cladding material is then placed on the waste plate, and the cladding material and the backing plate are welded by fillet welding.

Next, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings starting from FIG.

Here, FIG. 2 is a perspective view including a partial cross section of a welded joint obtained by the welding method of the present invention (however, the state before the patch plate is joined), and FIG. 3 is an exploded perspective view of the joint. It is.

In these figures, (10m) and (10b) are carbon steels that are base metals, and (li) and (llb) are carbon steels that have been clad on the surfaces of carbon steels (101) and (10b) by explosion bonding, etc. It is a cladding material selected from titanium, zirconium, and niobium made of materials that cannot be welded to carbon steel and has a lower coefficient of thermal expansion than carbon steel. (l,) is cut in parallel.

(To) is inserted into the above resection part α turret, totaling 411tl
It is a thin plate intermediate material made of silver alloy or silver alloy that is sandwiched between S and base metal (10m) and (10b), and it is well welded to carbon steel and cladding materials such as titanium. . The waste board (to) and the backing board (to be described later) are both made of the same material as the cladding materials (lla) and (llb), and the width of the waste board and intermediate material 0 is -(2/2/2) of the cutout part ti41. , ), and the width (L) of the backing plate (to) is determined to be one minute wider than the width (2j, ) of the cutout part Q turret. As shown in FIG. 2, the rotary electrode (P) is pressed against the waste plate (to) which is partially attached to the resection part 1 via the intermediate material.
) is pressed against the bottom ikil1m of the moving electrode (i
) by passing a high current between the tortoise & (1”), (
1') 4c The ink material at the corresponding position is melted and resistance welding US, (2) is performed, and the waste plate α$ is attached to the base material (101, (1011) through the resistance welding part (to), am). )K are integrally welded.The sacrificial plate (2) and cladding materials (lla) and (llb) are also joined by butt welding (to) and (l).The above resistance welding parts (to) and (to) are located close to the left and right ends of the cutout part Q to the extent that they do not interfere with the butt weld (to) and the weld.

Finally, cover the excised area and apply cluttering material (mouth &
), (llb) and the repeating backing plate (to) are welded inside the corner to the cladding materials (11&) and (llb) in the same manner as in Fig. 111.

Prior to these processes, an insertion hole was drilled through the base metal (10 m) and cladding material (11 m).
The test pipe (2) that goes down to the joint surface (2) between the backing plate (to) and the cladding material (for 11), and the base metal (
Insert intermediate material (to) and base metal (10 m) into the hole drilled.
A test/tube that reaches the same level as the joint surface with 0&) may be attached.

When the joint part joined in the above manner is exposed to high temperature, the carbon steel part (2jt) corresponding to the cutout part 0 tends to expand more than the waste plate (2) due to the difference in thermal expansion coefficient. However, since both are integrally joined by the welding part (as), the welding part (to), Ql, is the thermal expansion of the base metal and cladding material between the cutout part I and the welding part -. You only have to pay the difference, and welding (to).

The burden borne by the mouse is greatly reduced.

Also, if you insert test pipes (2) and (to),
Even if a crack occurs in the welded part Ill or (2) due to fatigue due to long-term operation, corrosive liquid that has seeped through the crack can be detected at an early stage, making it possible to prevent metal corrosion that could lead to a major accident. .

As described above, the present invention involves cutting out a part of the cladding material to form a groove exposing the carbon steel surface, and then welding them together, and then welding the cladding material to the exposed part of the carbon copper surface. Further, a scrap board made of the same material as the cladding material is placed on the intermediate material, and the butt part of the plate and the cladding material is welded using this welding, and the scrap board, the intermediate material, and the carbon steel are resisted. Welding is performed by welding, and then a backing plate made of the same material as the cladding material is placed on the waste plate, and the cladding material and the backing plate are welded by fillet welding. ), the thermal stress caused by the difference in thermal expansion between the cladding material and the carbon steel part can be borne by the thick metal body of the sacrificial plate 4.
The thermal stress borne in 1 is only the non-expansion difference between the cladding material and the coal Jim part between the welding part (to) and the resistance welding part (to), and the td contact part U*, Improves lifespan.

[Brief explanation of drawings]

FIG. 1 is a perspective view including a partial cross section of a joint portion of a conventional cladding, and FIG. Fig. 3 is an exploded perspective view of the joint. (Explanation of symbols) 101. 10b...Charcoal: IA steel, lla, llb
・ 7 Ladding material, 13... Intermediate material, 14...
Resection part, 15... Discard plate, 16... Patching plate, 18.
...Resistance welding part, 19... Welding part, 20... Fillet welding. Yamato Kobe Steel Corporation Representative Patent Attorney Takeshi Honjo

Claims (1)

[Claims] In a method of butt welding clad steel made by cladding carbon steel with a cladding material made of a single layer of titanium or zirconium, a part of the cladding material is cut off to form a groove that exposes the surface of the carbon steel, and the welding is performed by butting. Next, an intermediate material made of silver or silver alloy is placed on the exposed part of the surface of the vertical steel, and a waste plate made of the same material as the cladding material is placed on the intermediate material, and the waste plate and the cladding are welded. In addition to welding the butt part with the material,
The intermediate material and the carbon steel are welded by resistance welding, and then the cladding material and the porcelain backing plate are placed on the waste plate, and the cladding material and the backing plate are welded by fillet welding. Method of welding clad steel.