JPH0524981B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a joining ribbon using an Fe-based alloy. (Conventional technology) Solid phase joining using superplastic materials is already well known [for example, ("Superplasticity and metal processing technology": edited by Superplasticity Research Group (1980), Nikkan Kogyo Shimbun, p. .151)]. However, in general, many superplastic materials are difficult to process in normal processing, and although there is an idea for solid-phase bonding in which a thin strip of superplastic material is sandwiched between a sandwich sandwich (Japanese Patent Application Laid-Open No. 52-45567), Practical implementation was difficult. In the case of solid phase bonding, the material must be formed into a thin strip with a thickness of several mm or less, and conventionally known superplastic materials could not be processed in this manner at industrial cost. (Problems to be Solved by the Invention) An object of the present invention is to provide an Fe-based alloy ribbon for solid phase bonding that exhibits superplasticity and eliminates the various drawbacks of the prior art as described above. (Means for Solving the Problems) Thus, the inventors of the present invention repeatedly studied various materials for solid phase bonding, and found that duplex stainless steels exhibiting superplasticity were particularly excellent. Further research will be carried out to specify the alloy composition, and if there is a problem with workability, it is preferable to form a thin strip by directly forming the molten metal, so that it can be formed at the same time as superplasticity. The present invention was completed based on the knowledge that Here, the gist of the present invention is to contain one or two of Si≧0.5% and Mn≧1.7% by weight, and Si eq=Si+2/3 (Cr+Mo) and Mn eq=
Si eq and specified by Mn+2Ni+60C+50N
Mn eq satisfies the following relationship, 5/6Si eq-15/2≦Mn eq≦11/5Si eq-77/5, and has an alloy composition in which the remainder substantially consists of Fe,
This is a Fe-based alloy ribbon for bonding. Furthermore, the present invention preferably produces a thin strip with excellent superplasticity directly from a molten metal by rapid solidification, and achieves an extremely short diffusion distance based on adhesion due to excellent flow utilizing the superplasticity. It is possible to realize the diffusion bonding method using the
The target material is not particularly limited, but iron alloys are more preferred. Also, according to the rapid solidification described above, the thickness is 2 mm.
The following ribbons can be easily manufactured without any problems with workability. (Function) Next, the reason why the alloy composition is limited as described above in the present invention will be described. First, the limited Si eq and
Mn eq defines the range in which the ratio of α/(α+γ) is 0.2 to 0.8 under hot working conditions of 700 to 1200°C, and as long as such conditions are satisfied, the specific composition of each individual Regardless of α/(α+γ)
=0.2 to 0.8 is satisfied, and superplasticity is achieved. Preferably, 1.1Si eq−10.8≦Mn eq≦1.7Si eq−
14, and Si eq = 10-20. The preferred range of Si eq and Mn eq is the range shown by diagonal lines in Figure 1, which will be described later. This is more preferable, and this is also preferable from the viewpoint of ensuring the properties of the product. FIG. 1 is a graph summarizing the above-mentioned relationship between Mn eq and Si eq. As is clear from what has already been said, Si eq and Mn eq were first defined as the Si equivalent of the ferrite-forming element, and
and to obtain the Mn equivalent of the austenite-forming elements. In the case of the present invention, in order to adjust the two-phase structure using Si and Mn, each is defined as described above. In addition, the reason why they are limited to the above range is that in this range, a two-phase structure of α phase and γ phase occurs, and the ratio of γ phase during hot working is 0.2 to 0.8, resulting in excellent superplasticity. This is because it will be done. Also, 0.5% or more Si or 1.7% or more Mn
The purpose of the present invention is to provide a superplastic Fe-based alloy that does not necessarily require corrosion resistance and is inexpensive.
This is because Si or Mn is actively used, and in the present invention, an amount greater than that conventionally used as a deoxidizing agent is added. In the present invention, the upper limits of Si and Mn are not particularly limited, but when considering Fe as the third element, in order to obtain the desired two-phase structure, Si<10
%, and Mn<15%, tissue adjustment becomes easier. Therefore, according to one preferred embodiment of the present invention, the alloy composition is Si: 0.5-10% by weight and/or Mn: 1.7-15%, balance Fe. In addition, from the purpose of obtaining the above-mentioned two-phase structure of the present invention, the amount of Ni, Cr, or Mo added is not limited, but for economic reasons, each
Ni: 0-5%, Cr: 0-20%, Mo: 0-2.5%
limited to. If you want to ensure corrosion resistance, you can increase the amount of Cr or Mo as necessary. Therefore, according to another aspect of the invention, the alloy composition is Si: 0.5-10% by weight, and/or Mn: 1.7-15% by weight, and Ni: 5% by weight.
Hereinafter, it is composed of at least one of Cr: 20% by weight or less and Mo: 2.5% by weight or less, the balance being Fe and unavoidable impurities. The two-phase alloy according to the present invention includes Fe, Si, Cr,
In addition to Mo, N and C, if necessary, Cu≦1.0
%, Ti≦0.5%, Zr≦0.5%, Nb≦0.5%, V≦0.5
%, W≦1.0%, as well as small amounts of Re, Ca, and Ce.
Also included in the present invention are those containing unavoidable impurities. However, since Ti, Zr, Nb, and V easily form nitrides and reduce the amount of solid solution N that is effective for superplasticity, it is better not to add them if possible. Since C may generate carbides and impair the properties of the product, a lower C content is preferable. N is a powerful γ-forming element, and it diffuses more easily than Mn and Ni. Therefore, it helps the structural changes caused by the thermal activation process, making it easier to develop superplastic deformation, and it is also the cheapest. It is advantageous to contain as much as possible, preferably about 0.01 to 0.25%. As described above, in the present invention, as long as the α+γ type two-phase structure is exhibited, the excellent superplasticity phenomenon can be utilized. It has been confirmed that as long as the conditions shown in FIG. 1 are satisfied, the α+γ two-phase structure is not substantially changed at all. The method of manufacturing the ribbon according to the present invention is not particularly limited, but considering that two-phase alloys are generally difficult-to-process materials, rapid solidification is preferable, and ordinary single roll, double roll, or other methods are preferable. Applicable. Although the cooling rate is not particularly limited, it is preferably 100° C./sec or more because the finer the structure, the better the subsequent superplastic deformability. More preferably it is 10 ³ °C/sec or more. Further, the upper limit of the thickness of the ribbon is preferably 2 mm, since the thinner the thinner the thinner the cooling rate, the more efficient the bonding will be. Although there is no particular lower limit, it is set to 20 μm for reasons related to manufacturing the quenched ribbon. Although the thin strip obtained in this way can be used as is for solid-phase bonding, it is necessary to perform hot processing or cooling processing to improve the sheet surface properties and further refine the structure in the subsequent process. It's okay. These treatments significantly refine the structure through recrystallization during solid phase welding and improve superplasticity.
For this purpose, 50% and 20% or more are preferable, respectively. In order to achieve the above objective, the hot rolling temperature is preferably lower than 1200°C, more preferably 1000°C or lower.
It is best to do this at temperatures below ℃. When performing solid phase bonding using the ribbon for solid phase bonding obtained according to the present invention, the specific conditions are not particularly limited, but preferably, the bonding surface is first made a clean surface and then heated to 750 to 1200 ° C. Bonding may be performed while applying a pressure of 0.5 Kgf/mm ² or more. The reason why the temperature is limited to 750 to 1200℃ is that it is easy to obtain the superplasticity of duplex stainless steel in this range, and the structure of the solid phase joining material will not become coarse and its original properties will not be impaired. It is. More preferably, the temperature is 900 to 1100°C. Heating may be performed by any method, but in order to prevent scaling, heating is preferably performed in an N ₂ gas atmosphere containing a large amount of nitrogen, which is contained in a large amount in two-phase stainless steel. The compressive force for joining needs to be 0.5 Kgf/mm ² or more, and if it is too large, buckling and deformation will increase, so it is desirable to keep it at 10 Kgf/mm ² or less. Duplex stainless steel that has been joined by heating and pressure is cooled as it is, but if a sigma phase is formed during cooling, it will significantly impair toughness, so
Cool at a cooling rate of min or more, preferably 1000 ~
It is preferable to rapidly cool the material after heating it to around 1200.degree. C., since this is substantially the same as solution treatment. The material used for bonding is not particularly limited, but iron has good diffusion bonding properties and is unlikely to produce Kirkendall voids caused by significant differences in diffusion coefficients between different elements or intermediate phases consisting of intermetallic compounds that degrade mechanical properties. Base alloys are preferred, low alloy steels,
Austenitic and ferritic stainless steels can be used, and Ni-based alloys can also be used. Next, the present invention will be explained in more detail with reference to Examples, which are shown merely as examples of the present invention.
The present invention is not unduly limited thereby. Example In this example, Fe-Mn is used as an inexpensive two-phase iron-based alloy.
-Si ternary alloy was used. The molten metal having the chemical composition shown in Table 1 is sprayed onto the surface of a 300 mm diameter double roll made of cemented carbide or a 400 mm single Cu roll rotating at 20 to 2000 rpm from a nozzle with a diameter of 0.5 x 15 mm, and the thickness is 50 to 300 μm. A quenched ribbon with a width of 15 mm was prepared. Either as cast or after a combination of hot rolling and cold rolling for some of them, the above thin strips were sandwiched between various bonding materials with 15 mm diameter end faces finished with #600 emery paper and _N2 Local high-frequency heating in a gas atmosphere,
The temperature was raised to a predetermined temperature, the pressure was applied at a predetermined pressure for a predetermined time, and the mixture was allowed to cool. From these, tensile test pieces with a parallel part diameter of 10 mm and a length of 40 mm were cut out and subjected to a tensile test at room temperature. The respective conditions and test results are shown in Table 2, and it can be seen that solid phase bonding is easily performed according to the present invention.

【table】

[Table] 3
*2: Mn eq=Mn+2Ni+60C+50N
*3: N in parentheses is the remaining valid value fixed as TiN
(Solid solution) Indicates N.

【table】

[Table] **: ○: Fracture of base metal, △: Fracture of joint, strength is same as base material, ×: Fracture of joint, strength of base material fracture

[Brief explanation of the drawing]

The accompanying drawing is a graph showing the relationship between Mn eq and Si eq in the present invention.

Claims (1)

[Claims] 1. One or two of Si≧0.5% and Mn≧1.7% in weight%
contains seeds and Si eq=Si+2/3(Cr+Mo) and Mn eq=
Si eq and specified by Mn + 2Ni + 60C + 50N
Mn eq satisfies the following relationship, 5/6Si eq-15/2≦Mn eq≦11/5Si eq-77/5, and has an alloy composition in which the remainder substantially consists of Fe,
Fe-based alloy ribbon for solid phase bonding. 2. The Fe-based alloy ribbon for solid phase bonding according to claim 1, which is formed directly from a molten metal into a ribbon. 3. The first claim in which the thickness is 2 mm or less
2. Fe-based alloy ribbon for solid phase bonding according to item 1 or 2.