JPH02104481A - Zirconium clad steel material and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain Zr clad steel material with satisfactory joining strength at a low cost by providing a low C steel layer having specific composition as an intermediate layer between steel material as base metal and Zr material as cladding material. CONSTITUTION:The title clad steel material consists of the steel material 3 as base metal, the Zr material 1 as cladding material and the metallic intermediate layer 7 which is rolled and joined between the faces in opposition of both materials 3 and 1. The metallic intermediate layer 7 has contents, by weight of, <=0.03% C, <=0.50% Si, <=0.80% Mn and contains, by weight with respect to C, >=3 for >=1 kind among <=0.50% Ti, <=0.10% Nb, <=0.50% Mo as C fixing elements in the steel and the balance low C steel which is Fe (% by weight) essentially. By this method, the Zr clad steel material with satisfactory joining strength can be obtained at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a zirconium clad steel material with excellent bonding strength, and a method for manufacturing the zirconium clad steel material.

<Prior art and its challenges> The so-called "craft material", which is made by laminating and integrating dissimilar metals in layers, combines the excellent properties of each clad material and compensates for the shortcomings of each, which cannot be obtained with a single metal. It is one of the materials whose use in various fields is increasing significantly due to its excellent properties and relatively advantageous price.

By the way, zirconium, which has recently attracted attention as a corrosion-resistant material for the chemical industry, has excellent corrosion resistance against concentrated sulfuric acid, two strong alkalis, hydrochloric acid, etc., which titanium cannot withstand. Because titanium is considerably more disadvantageous than titanium, its application as a practical material, except for special parts, has tended to be delayed. However, recently, due to significant advances in clad material manufacturing technology, it has become possible to manufacture ``zirconium clad steel'', which uses steel as a base material and zirconium as a composite material, making it possible to take advantage of zirconium's excellent corrosion resistance. In addition, zirconium-clad steel materials have been attracting a lot of attention because they can reduce manufacturing costs by reducing the amount of zirconium used by cladding with steel materials.

However, the so-called " In the "rolling method", when joining the steel material as the base material and the zirconium material as the mating material by hot rolling,
There is a problem in that zirconium carbide is generated on the joint surface, significantly deteriorating the joint performance, and this has been a major obstacle to the practical application of zirconium clad steel materials produced by the rolling method.

Therefore, the purpose of the present invention is to find a method for manufacturing zirconium clad steel materials by a rolling method that does not cause zirconium carbide to form on the clad bonding surface and deteriorate the bonding properties, and which is sufficiently satisfactory for practical use. It is an object of the present invention to provide a low-cost zirconium clad steel material with high bonding strength.

Means for Solving the Problems> Therefore, the present inventors conducted repeated experiments and research from various viewpoints in order to achieve the above object, and found that [a steel base material and a zirconium laminated material are joined by a roll method] In this case, a low carbon steel of a specific composition is inserted as an intermediate layer between the base material and the composite material, or an intermediate layer consisting of the low carbon steel and nickel is interposed so that the nickel is on the base material side. By hot-rolling this in a temperature range of 650 to 1200°C, the bondability between the steel base material and the zirconium laminated material is improved, making it possible to stably obtain a zirconium-clad steel material with excellent bonding strength. ”, we have obtained new knowledge.

The present invention has been made based on the above findings, and includes [a zirconium clad steel material, a steel material as a base material,
It consists of a zirconium material as a bonding material and a metal intermediate layer rolled and joined between the opposing surfaces of these two, and the metal intermediate layer has a carbon content of 0.03% or less (hereinafter, % representing the component ratio is (% by weight).

Si content: 0.50% or less.

Sound content: 0.80% or less and as a carbon fixing element in steel. Ti: 0.50% or less.

Nb: 0.10% or less.

It is a low carbon steel containing one or more of Mo: 0.5% or less in a weight ratio of 3 or more to C, and the balance is substantially Fe, or
Or, it has a two-layer structure with a nickel layer adjacent to the base metal side of the low carbon steel layer, and furthermore, it has a two-layer structure with a nickel layer adjacent to the base material side of the low carbon steel layer. After overlapping the zirconium material and the zirconium material as a mating material to form a clad assembly material, at least the overlapping portion and the zirconium material are sealed to form a clad assembly, and then the internal void of the clad assembly is subjected to exhaust treatment. After that, the clad assembly is hot-rolled and joined at a temperature range of 650 to 1200°C, thereby making it possible to stably produce a zirconium clad steel material with excellent joint strength.

It should be noted that the creation of the clad assembly requires the first step in order to prevent oxidation of the zirconium composite material during hot rolling.
As shown in the figure, two clad S and standing materials are placed one on top of the other with the zirconium materials (1) facing each other, with a release material (2) interposed between both zirconium materials (11, (1)), and then Steel material (3) located on the outside.

(3) For example, the entire circumference between the pads +41. (41 and weld metal (5).

(5), or as shown in Fig. 2, a dummy steel material (6) is further superimposed on the zirconium material (11 side) of the clad assembly material, and then a dummy steel material (6) is placed on the outside steel material (31, (6)). ), for example, a backing plate (4),
(41) and the weld metal (51, (51).

By the way, in Figures 1 and 2, the metal intermediate layer inserted between the base material and the base material is made of low carbon steel (7) and nickel (8).
(Although the nickel layer can be a foil or plating film), this metal intermediate layer is a low carbon layer (7).
It goes without saying that there may be only one layer of .

Here, in the present invention, the structure of the zirconium clad steel material and the reason why the manufacturing conditions thereof are limited as described above will be explained in detail along with their effects.

<Function> First, in the present invention, the reason why a "layer of low carbon steel with a specific composition" is provided as an intermediate layer between the steel material as the base material and the zirconium material as the mating material is that In addition to being clad with sufficient bonding strength to the laminated material, this intermediate layer allows carbon in the base material, the rope material, to diffuse into the zirconium material, forming brittle zirconium carbide between the base material and the composite material. This is because it is suppressed and a decrease in bonding strength is prevented. In this case, the intermediate layer is a "double layer consisting of a low carbon steel layer having the specific composition and a nickel layer".
By arranging the nickel layer side so that it faces the steel material that is the base material, the interposition of the nickel layer facilitates joining the base material and the low carbon steel, and also allows the bonding of C in the base material to be performed. The diffusion of is more effectively suppressed, making it possible to maintain a stronger and more stable Ladd junction.

The reason why the composition of the low carbon steel serving as the intermediate layer is limited as described above is as follows.

a) C content: C diffuses into the zirconium material and forms brittle Zr carbide, which significantly impairs bonding properties. Therefore, it is desirable that the content of C be as low as possible, but there is no way to prevent its unavoidable contamination into the steel. It is a difficult element. In the present invention, Ti, Nb
Alternatively, efforts have been made to fix C as a carbide to an extent that does not inhibit bonding properties by adding a carbide-forming element of Mo, but even so, if the C content exceeds 0.03%, the above disadvantages cannot be suppressed, The C content was regulated to 0.03% or less.

b) Si content Si is also an element that should be reduced as much as possible as it has a negative effect on cladding bondability.If its content exceeds 0.50%, the above-mentioned negative effects cannot be ignored, so the Si content should be reduced as much as possible. It was regulated at 0.50% or less.

c) Mn content Although Mn does not need to be added at all from the viewpoint of ensuring bondability, it is an element that is inevitably mixed into steel. However, if a large amount of Mn is contained, the workability of the low carbon steel itself is inhibited and there is no industrial benefit, so the permissible Mn content is set at 0.80% or less, which is the level of ordinary steel.

d) Ti, Nb, Mo content Since these elements tend to combine with C to form carbides, it is necessary to fix the C that is unavoidably contained in low carbon steel,
One or more elements are added to prevent the diffusion of C into the zirconium material side and the formation of Zr carbide on the bonding surface and improve bonding properties, but the total amount of these elements is If the weight ratio is less than 3, a sufficient joining property improvement effect cannot be ensured.On the other hand, if the Ti content is 0.50%, the Nb content is 0.10%, and the Mo content is 0.
If each content exceeds 5%, the workability of low carbon steel will be reduced and no industrial benefit will be obtained. Therefore, Ti,
Nb and Mo: Tt: 0.50% or less, Nb
: 0.10% or less, M.

: 0.5% or less, and one or more types should be added in a total amount of 3 or more in terms of weight ratio to C.

When a zirconium clad steel material is constructed with an intermediate layer as described above, there is no concern about deterioration of joint strength even when used under various heating conditions, but zirconium clad steel materials manufactured by a rolling method are If the above-mentioned intermediate layer is inserted during the bonding process, the formation of Zr carbide between the base material and the mating material during the bonding process can be effectively suppressed, and deterioration of bondability can be prevented. As stated earlier.

The reason why the hot rolling temperature during production of zirconium clad steel material was set at 650 to 1200°C is as follows. That is, when rolling the clad assembly, if the rolling temperature is lower than 650° C., there is a risk that warping may occur during rolling or the clad assembly may be destroyed, making rolling impossible.

On the other hand, the upper limit of the heating temperature normally set during hot rolling of steel materials is 1200°C, and there is no benefit in heating at a temperature higher than this during hot rolling in the present invention.
If heated above 0°C, the melting point will decrease due to mutual diffusion of Zr and Fe, and there is a risk that the clad material will melt.

Next, the effects of the present invention will be specifically explained using examples.

<Example> A steel plate (thickness 120 m1) as a base material and a zirconium plate (as a laminating material) with chemical compositions as shown in Table 1 were used.
``thickness 30 mm)'', ``low carbon steel thin plate as intermediate metal layer (thickness l+u)'', ``nickel thin plate as intermediate metal layer (thickness 0,3u+)'', and dummy steel plate (thickness 40*n
A cladding assembly was prepared by combining these plates as shown in Figure 2. There are two types: (1) and (2) a layered nickel plate.

Next, the internal voids of these clad assemblies were evacuated to 10-2 Torr in a conventional manner, and then heated to the temperature shown in Table 2 and hot rolled.
Zirconium clad steel plates of 3mm, 0.1mm and 0.03mm were manufactured.

When the zirconium clad steel plate thus obtained was subjected to an ultrasonic flaw detection test, it was found that the zirconium clad steel plate produced by the method according to the present invention had no peeling at the joints.

The mechanical properties of each zirconium clad steel plate were also investigated, and the results are also shown in Table 2.

From the results shown in Table 2, it can be confirmed that according to the present invention, zirconium clad steel materials with high bonding strength can be stably obtained, and it is clear that the present invention brings extremely useful effects industrially.

[Brief explanation of drawings]

The drawings are conceptual diagrams showing an example of how to assemble a cladding material that can be used in the method for manufacturing zirconium clad steel materials according to the present invention, and FIGS. 1 and 2 are different examples. In the drawing, ■...Zirconium laminating material, 2...'WI
Eif agent. 3... Steel base material, 4... Backing plate. 5...Weld metal, 6...Dummy steel material. 7...Low carbon steel, 8...Nickel.

Claims (5)

[Claims] (1) Consisting of a steel material as a base material, a zirconium material as a bonding material, and a metal intermediate layer rolled and bonded between the opposing surfaces of these two, the metal intermediate layer has a carbon content of 0.0
3% or less, Si content: 0.50% or less, Mn content: 0.80% or less, and as a carbon fixing element in steel: Ti: 0.50% or less, Nb: 0.10% or less, Mo : Contains one or more of the following: 0.5% or less in a weight ratio of 3 or more to C, and the remainder is substantially Fe (weight% or more). , zirconium clad steel. (2) Consisting of a steel material as a base material, a zirconium material as a bonding material, and a metal intermediate layer rolled and joined between the opposing surfaces of these two, the metal intermediate layer has a C content of 0.0
Less than 3%. Si content: 0.50% or less, Mn content: 0.80% or less, and as a carbon fixing element in steel, Ti: 0.50% or less, Nb: 0.10% or less, Mo: 0.5 % or less in a weight ratio of 3 or more to C, and the balance is substantially Fe (weight % or more), adjacent to the base metal side of the low carbon steel layer. A zirconium clad steel material characterized by being composed of two layers: a nickel layer and a nickel layer. (3) After the steel material as a base material and the zirconium material as a mating material are overlapped to form a clad assembly material by interposing the metal intermediate layer described below, at least the overlapped portion and the zirconium material are sealed. Production of a zirconium clad steel material, which is characterized in that the clad assembly is formed into a clad assembly, and then the internal void of the clad assembly is evacuated, and then the clad assembly is hot-rolled and joined at a temperature range of 650 to 1200°C. Method. C content: 0.03% or less, Si content: 0.50% or less, Mn content: 0.80% or less, and Ti: 0.50% as a carbon fixing element in the steel. Hereinafter, low carbon containing one or more of Nb: 0.10% or less and Mo: 0.5% or less in a weight ratio of 3 or more to C, and the balance is substantially Fe (weight% or more) A layer of steel, or a two-layer structure consisting of this low carbon steel layer and a nickel layer adjacent to the base material side. (4) Creation of the clad assembly consists of stacking two clad assembly materials with the zirconium materials facing each other with a release material interposed between both zirconium materials, and then stacking the entire cladding material between the outer steel materials. 4. The method for producing a zirconium clad steel material according to claim 3, wherein the method is performed by sealing the periphery. (5) The clad assembly is created by further overlapping a dummy steel material on the zirconium material side of the clad assembly material, and then sealing the entire periphery between the steel materials located on the outside. Method for manufacturing zirconium clad steel.