JPS61123486A - Manufacture of double layer clad round bar - Google Patents

Abstract

PURPOSE:To obtain a good clad round bar by brining a tubular shell whose thermal expansion coefficient is smaller than that of a round bar, to an open- working to a vertical split, covering the round bar with it, welding the open- working part, and thereafter, heating it, and executing a diffused junction by utilizing the difference of a thermal expansion of both members. CONSTITUTION:A Zr pipe 1 and a round bar 2 of steel having a high alpha value are worked to a size by which a diffusing junction can be executed. Subsequently, a vertical opening part 4 is provided by bringing the Zr pipe 1 to a groove working, the round bar 2 is covered with said pipe, and the vertical opening part forms a vertical weld zone by using a welding material Zr. Thereafter, this assembly material is brought to a diffused junction processing and a double layer clad steel round bar is formed. Accordingly, according to this method, since the round bar is not inserted into the Zr pipe, its installation is executed easily, and even in case of that having a large diameter and a long size, it can be prepared easily. In this regard, this method can be applied to other pipe of a material having a low alpha value than a pure Zr pipe.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of manufacturing a double-clad round bar.

(Prior Art) Zirconium titanium and their alloys (hereinafter referred to as Zr) are widely used as materials for chemical vessels and nuclear reactors due to their excellent corrosion resistance and heat resistance. ), and other parts are required to use inexpensive materials.In order to meet this requirement, for plates, ZR clad steel using explosion bonding or diffusion bonding has been developed and is now in practical use. However, it is not commonly applied to round bars such as rolls or shafts.

The present inventors inserted a round bar of Zr'WK steel and heated it, and filed a patent application on the same date as the present invention for a diffusion bonded clad steel pipe that utilizes the difference in coefficient of thermal expansion (hereinafter referred to as α) between the two materials. Z
There is a drawback that there is a limit to the size of the gap (difference between the inner diameter of the Zr tube and the outer diameter of the round bar) between the two before heating due to the relationship between r and the a value of the steel.

That is, when carbon steel or low alloy steel is used for the inserted round bar, Zr
The difference in a value between the
gap between B) Since the diffusion bonding properties between Zr and carbon steel are not very good, it is necessary to use Ti, which does not cause intermetallic compounds between them.
Since it is necessary to install Mn, Ni or a combination of these foils or coatings, if the gap between the art materials is small, Zr
Workability is extremely poor when inserting a steel round bar into a pipe. On the other hand, when austenitic stainless steel is used for the inserted round rod,
Since the difference in α value with zr is large, the gap before heating can be made large and it is easy to insert (for example, a 0°2 gap with an 80φ round bar), but a large shrinkage stress is generated during the cooling process after joining. As a result, cracks occur at the joint, making it difficult to obtain a good rad round bar.

(Problems to be Solved by the Invention) To manufacture a clad round bar that can be easily attached to an unheated Zr tube and a core material and has high bonding strength when manufactured by Z-clad steel roll or ring metal diffusion bonding. It is intended to provide a method.

(Means for Solving the Problems) That is, the present invention involves preparing round bars to be joined and tubular shells having a smaller coefficient of thermal expansion than the round bars to dimensions that allow diffusion bonding, and then forming one or more tubular shells. Split vertically and open, place the opened outer shell over a round bar, and open the shell SF: Longitudinal welding, and the assembled materials are diffusion bonded using the difference in thermal expansion between the two members.
- A method for manufacturing a double-layer clad round bar.

The present invention can be advantageously applied to manufacturing stirring shafts and rolls for chemical reactors.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 12 are explanatory diagrams of the procedure of one embodiment of the present invention, FIG. 3 is an explanatory diagram of another embodiment of the present invention, and FIG. 4 is a sectional view taken along line I-1 in FIG. Al t (BI-(cl
each represents a different embodiment. FIG. 5 is an explanatory diagram of an embodiment proposed in a patent application dated the same date as the present invention.

In the figure, 1 is Zr12, which is a steel material that is cheaper, has higher strength, and has a higher α value than Zr, and 3 is an insert material to increase the joint strength, and is made of Ti, MO, Ni, or a combination of these foils or plating. This is a coating provided on the surface of Zr 1 or steel material 2 using a coat or ink such as thermal spraying. 4
5 indicates a vertical opening, 5 indicates a vertical welded portion, 6 indicates a groove, and 7 indicates a Zr plate.

The means proposed on the same date was the Zr tube 1 as shown in Figure 5.
A round bar 2 of steel with a high alpha value is inserted into the steel plate, and this is diffusion welded to form a double-layer clad steel, but this method has the problems described above.

In contrast, in one embodiment of the present invention, Zr
A tube 1 and a round bar 2 made of high alpha value steel are machined to dimensions that allow diffusion bonding, and a bevel is formed on the Zr tube 1 to provide a vertical opening 4t, as shown in FIG. Next, the ZR tube 1 with the vertical opening 4 is covered with a round bar 2 made of steel with a high α value, and as shown in FIG. Welding is performed to form a vertical weld portion 4. Thereafter, this assembled material is processed by diffusion bonding to form a double-layer clad steel round bar.

FIG. 5 shows a part of another embodiment of the present invention. In the first embodiment, the beveling process was performed at one place, but in this embodiment, the beveling process was performed at t-2 places, and the separation process was performed at t-2 places. Lo part 4t-2
This is a separate location. The subsequent steps are the same as in the embodiment described above.

FIG. 4 is a view taken along the line 1'-1 in FIG. 5, but shows a different embodiment. Fig. 4 (AJ is the embodiment shown in Fig. 5 itself, and Fig. 4 (83) is a high α value steel circle in contact with the M1 opening part 4 of the ZR pipe when carrying out the embodiment shown in Fig. 3. A case is shown in which grooves 6 are provided on the surface of the rod.This is to ensure that sufficient welding waves are formed.

FIG. 4 (Cil is further filled with Zr in the groove 6 of FIG. 4 (Bl).
The plate 7 is fitted. This is because the Zr tube 1 is thin-walled.
If there are grooves (cavities) in rolls, etc. that are subjected to increased NLP pressure, they may deform in those areas, and since there are notches in the weld root, cracks may occur when repeated stress is applied. This is to prevent this.

Diffusion bonding is a method of heating materials to a temperature below their melting point in a vacuum or an inert gas, applying appropriate stress, and bonding, and is a part of solid-state bonding. In the present invention, this stress load does not use an external force, but utilizes thermal stress due to the α difference between the art materials. That is, the α of Zr in the welding temperature range is less than A for carbon steel, and about 14 for austenitic stainless steel.
69, by attaching all the round steel bars with a large α to the Zr shell with a small α and heating the steel material, the Zr f will try to expand, so sufficient stress will act on the Zr-steel interface for bonding. . The magnitude of this stress affects the bonding strength, and naturally affects the size of the α-value gap between the two materials and the heating temperature.

The present invention is capable of assembling the Zr outer layer and the steel inner core by using the procedure described above instead of the conventional method of inserting a round rod into the Zr tube. However, it is easy to install, and even large-diameter and long-length products can be manufactured easily. It should be noted that fusion welding of Zr and carbon steel forms a brittle intermetallic compound at the bond, which may result in cracks. Therefore, in the case shown in Fig. 4 (A)', it is necessary to leave the undissolved part in a state where the undissolved part is left in order to prevent the base material (round bar) tl from melting, and when using a thin-walled Zr tube, is not appropriate. As mentioned above, the means shown in FIG.
] was installed, thereby completely preventing cracks from occurring. In addition, the Zr shell is completely welded by fitting the Zr piece t into this space in Figure 4 (tc+), and in this case, the processed steel and the Zr piece, as well as the Zr pipe and the Zr piece, are also diffusion bonded during subsequent heating. Therefore, a completely integrally clad round bar is obtained. On the other hand, in such a welded structure, shrinkage and deformation of the welded metal causes
The gap caused by the precision of the swordsmith between the two parts disappears. Rather, the shell becomes in a state where the round rod is squeezed, which is advantageous for subsequent diffusion bonding.

Example Carbon steel (334179゜6φ) with a thickness of 0.05mm N1
, Mo with thickness 0.05, thickness o, i with τ1 of 1ias
r sequential winding, pure Zr tube (ASJg 3B-551°R6
0702: Outer diameter 100.0φ, inner diameter 80.0φ), cut in half, and cover with gas shield f (2Q 1
3/win), 2■φ Zr@i-Use 100
MiG welded at the speed of mlI/Win 5
X I Q-' 780℃~870℃ in Torr vacuum
Diffusion bonding was performed by heating in the range of 2 hours. As a result, z
It was found that a pull-out strength of 2 to 5 kg/us2 was obtained between r-carbon steels, and a good bonded body with no defects was obtained even by microstructural observation. In the case of the conventional method of inserting a carbon steel round bar into a Zr tube, the gap between the CZr + insert material and the round bar before side heating is less than 0.1 mm, making it extremely difficult to insert the round bar. On the other hand, the method of the present invention allowed for smooth installation regardless of the gap.

The present invention has been explained above using @zr as a representative, but pure Z
In addition to r-tubes, the present invention can be similarly applied to tubes made of materials with low α values such as Zr alloy, tantalum, mental alloy, titanium, and titanium alloy.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are explanatory diagrams of the procedure of one embodiment of the present invention,
FIG. 3 is an explanatory diagram of another embodiment of the present invention, and FIG. 4 is an explanatory diagram of another embodiment of the present invention.
In the 1-1 cross-sectional view of the figure, its (Al, (Bl?
C1 each represents a different embodiment. FIG. 5 is an explanatory diagram of an embodiment proposed in a patent application filed on the same date as the present invention. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] After processing the round bar to be joined and a tubular outer shell having a coefficient of thermal expansion smaller than that of the round bar into dimensions that allow diffusion bonding, the tubular outer shell is vertically divided into one or more pieces and opened, and the opened outer shell is made into a round bar. 1. A method for manufacturing a double-layer clad round bar, which comprises longitudinally welding the opened parts over each other, and then diffusion-bonding the assembled materials by utilizing the difference in thermal expansion between the two members.