JPH0140092B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly vibration-absorbing and highly corrosion-resistant iron-based alloy. Conventionally, corrosion-resistant cast alloys such as stainless steel, manganese bronze, and aluminum bronze have been used for materials such as marine propellers, various stirring propellers, and impellers. Among these stainless steels, 25Cr-6Ni series (JIS-SCS11) or
20Cr-10Ni (JIS-SCS13) alloys are typical, but these alloys have problems with product stability, corrosion resistance (especially crevice corrosion), mechanical strength, and damping ability, so further improvements are needed. It has become required. It is an object of the present invention to improve the above-mentioned properties and provide an alloy having even better vibration absorption, corrosion resistance and mechanical properties. Therefore, as a result of numerous studies, the present inventors determined that the weight ratio of chromium 20.1 to 35
%, cobalt 1.2 to 19%, copper 0.01 to 3%, and the balance iron, as subcomponents of molybdenum, tungsten 10% or less, niobium 5% or less, aluminum, titanium 3% or less, vanadium, tantalum 2% or less , manganese, zircon 1.5
It has been found that an alloy containing 0.01 to 40% of one or more of phosphorus and lead of 1% or less is suitable for this purpose. The method for producing the alloy of the present invention is based on the weight ratio of chromium
An alloy consisting of 20.1-35%, cobalt 1.2-19%, copper 0.01-3% and the balance iron, with sub-components of molybdenum, tungsten 10% or less, niobium 5% or less, aluminum, titanium 3% or less, vanadium, tantalum 2%. Below, zircon, manganese 1.5
(A) Homogeneous solution treatment to a temperature below the melting point of the alloy due to homogeneous solution treatment.
A process of heating at a high temperature of 500℃ or higher for 1 minute or more and 100 hours or less, and then cooling it; (B) A process of performing the above-mentioned cold processing after cooling; (C) A process of performing the above-mentioned cold processing at a temperature of 900℃ or below. 1 minute or more
Heating for 100 hours or less, then heating at 1°C/sec to 1
By performing a slow cooling process at a rate of ℃/hour and heat treatment, we obtained an alloy with a damping capacity of Q ^-1 of 5 × 10 ^-3 or more and a corrosion-free alloy that can withstand a pitting potential of at least 300 mV or more. Features. In the method for producing the alloy of the present invention, the solution treatment is heating at a temperature above the magnetic transformation point of approximately 500°C and below the melting point for 1 minute to 100 hours in order to homogenize the structure of the alloy. In the case of laboratory scale items with small mass and high temperature heating close to the melting point, heating for 1 minute or more is sufficient;
100 when heating at a relatively low temperature near 500℃
Requires long-term heating of less than 1 hour. Cooling after this homogeneous solution treatment is rapid cooling (1/sec
Rapid cooling at ℃/sec/or more) or gradual cooling (1℃/sec to 1
℃/hour). When an alloy molded body heated to a temperature above 500℃ and below the melting point is slowly cooled, the damping capacity improves because no strain occurs in the structure.
Corrosion resistance improves, but mechanical properties deteriorate slightly. On the other hand, when a molded body of an alloy subjected to homogeneous solution treatment is rapidly cooled from a high temperature state, the mechanical properties are improved even if the damping capacity and corrosion resistance are slightly decreased. Next, when the cold working of (B) is applied to the slowly cooled material of the heat treatment of (A), the mechanical properties are significantly improved. Moreover, when the cold working of (B) is applied to the heat treated material of (A) which has been rapidly cooled, the mechanical properties are further improved. Next, in order to improve the mechanical properties of the alloy compact obtained by the heat treatment in (A), cold working in (B) is applied, which causes some distortion in the structure, slightly deteriorates the corrosion resistance, and reduces the damping capacity. is slightly lower, and workability is slightly worse. For this purpose, in order to perform reheat treatment (C), heat at a temperature of 900°C or less for 1 minute to 100 hours or less, at 1°C per second.
When the structure is homogenized again by slow cooling at a rate of 1°C or more per hour, the damping capacity is improved, corrosion resistance is high, mechanical properties (tensile strength etc.) are improved, and workability is also improved, damping capacity Q ^{- This} makes it possible to obtain a material with a high attenuation capacity of 5 x 10 ^-3 or more and a corrosion-free material that can withstand a pitting potential of at least 300 mV or more. Therefore, generally, the above characteristics can be easily obtained by rapidly cooling a material that has been solution-treated at a high temperature, cold working it, and then tempering it by heating it at a low temperature. Next, the method for producing the alloy of the present invention will be explained in more detail. In the present invention, first, appropriate amounts of iron, cobalt, chromium, and copper are added as main components in the above alloy composition range, and additional subcomponents are added, and then melted in an ordinary melting furnace in air, inert gas, or vacuum. After that, manganese, silicon, titanium,
A small amount (approximately 1% or less) of aluminum, zircon, Mitsushi metal, calcium, etc. is added, harmful impurities are removed, and the molten alloy is thoroughly stirred to create a compositionally uniform molten alloy (all added elements of approximately 1% or less are in the ingot). These castings can be produced by casting the ingot into a shape suitable for the intended use, or by forging and rolling or swaging the ingot at room temperature or at a temperature below the melting point to form the material. Alternatively, the formed body is subjected to heat treatment consisting of the following (A), (B) and (C). (A) Below the melting point of the alloy due to solution treatment, 500
After heating at a high temperature of ℃ or higher for 100 hours or less, cooling is performed by rapid cooling or slow cooling. (B) Perform cold working after cooling as described above. (C) After cold working of (B), 100°C for more than 1 minute at 900℃ or less
The mixture is heated for up to an hour and then slowly cooled at a rate of up to 1°C per second. As mentioned above, the reason for performing the preliminary stage of solution treatment, that is, the process of melting the alloy, in an inert gas or vacuum atmosphere is to prevent impurities from entering the solution during the metal melting process. In order to remove impurities that were present in the solution from the beginning, one or more of manganese, titanium, aluminum, zircon, Mitsushimetal, and calcium is added in a small amount of 1% or less to deoxidize. It is preferable to remove harmful impurity inclusions, mainly in the form of oxides, to obtain a high damping capacity, high corrosion resistance iron-based alloy. However, since these deoxidizing agents are added for the purpose of deoxidizing, it is sufficient to add a very small amount of 1% or less, and better results can be obtained by ensuring that these components do not remain in the final product. Next, embodiments of the present invention will be described. After melting approximately 1 kg of iron, chromium, copper, and cobalt having the composition shown in Table 1 in an alumina crucible in a high-frequency induction electric furnace, the molten metal was thoroughly stirred and cast into an iron mold to form a 35 mm x 35 mm square shape. Obtained an ingot. Next, this was heated at 1000℃ for 1 hour, cooled at a rate of 100℃/hr, and then further cold-worked by 95% to form a round bar with a diameter of approximately 8mm, which was used for corrosion resistance tests, and a portion was forged. The wires were made into diameters of 5 mmφ by cold drawing, and round wires with diameters of 2 mmφ and 0.55 mmφ were obtained by cold drawing.The wires were then cut to appropriate lengths and used in cold working conditions for tensile tests and damping capacity tests. Furthermore, after heating these at 900°C for 1 hour, they were cooled at a rate of 100°C/hr and used for a re-annealing state test. The corrosion resistance test was conducted using the anodic polarization corrosion test method and the crevice corrosion test method, and the damping capacity test was conducted using the torsional vibration method at a maximum shear strain amplitude of 0.8×10 ^-4.The results are shown in Tables 1 to 4 and Figure 1. I got it.

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[Table] As is clear from these tables, the quaternary to six-element alloys of the present invention have very good corrosion resistance, mechanical properties, and damping capacity characteristics, and are superior to 25Cr-6Ni or 20Cr-10Ni.
Much superior to stainless steel. Therefore, the alloy of the present invention is very suitable as a material for propellers for rice crackers, various stirring propellers, impellers, and various other devices that require high corrosion resistance, high vibration absorption, and mechanical strength. Finally, the reason for limiting the composition of the alloy of the present invention will be described. First, in the Fe-Cr-Co-Cu quaternary alloy
The reason why the composition is limited to 20.1 to 35% Cr, 1.2 to 19% Co, 0.01 to 3% Cu, and iron balance is that the high damping capacity and high corrosion resistance that are the objectives of the present invention cannot be obtained outside of these composition ranges. Not only that, but also the workability deteriorates. In the composition of the Fe-Cr-Co-Cu quaternary alloy of the present invention,
Part of iron, chromium, cobalt and copper is replaced with molybdenum, tungsten 10% or less, niobium 5% or less, aluminum, titanium 3% or less, vanadium, tantalum 2% or less, manganese, zirconium
Total amount of one or more types of 1.5% or less 0.01-40
Even if the substitution is made by %, the desired target properties can be obtained. Fe−Cr−Co−Cu−Mo, Fe−Cr−Co−Cu−
In the W, Fe-Cr-Co-Cu-Nb based quinary alloy, molybdenum and tungsten are each kept at 10% or less and niobium at 5% or less because if the content is higher than this, the damping performance characteristics aimed at by the present invention cannot be obtained. Not only that, but also the workability deteriorates. Fe−Cr−Co−Cu−Al, Fe−Cr−Co−Cu−Ti
The reason why the content of aluminum and titanium in the five-element alloy is set to be 3% or less each is because if the content is more than 3%, not only will the damping properties that are the object of the present invention not be obtained, but also the corrosion resistance and workability will deteriorate. Fe-Cr-Co-Cu-V, Fe-Cr-Co-Cu-
In the five-component alloy of Ta, Fe-Cr-Co-Cu-Zr, vanadium and tantalum are each less than 2% and zirconium is less than 1.5%.If the content is more than that, the damping characteristics aimed at by the present invention cannot be obtained. Not,
This is because mechanical strength and workability deteriorate. Fe−Cr−Co−Cu−Mn, Fe−Cr−Co−Cu−
P, Fe-Cr-Co-Cu-Pb, Fe-Cr-Co-Cu-
In S-based quinary alloys, manganese is 1.5% or less, phosphorus,
The reason why the content of lead and carbon is set at 1% or less is that if the content exceeds 1%, not only the damping performance characteristics targeted by the present invention cannot be obtained, but also the workability and corrosion resistance deteriorate. The general tendency of the properties of each component of the alloy of the present invention is as follows.

[Table] ×...Poor Figure 1 shows the Fe-Cr-Co-Cu vibration-absorbing corrosion-resistant alloy of the present invention and the conventional 25Cr-6Ni stainless steel.
This is a comparison curve diagram of the pitting corrosion potential and current of 20Cr-10Ni stainless steel.As is clear from Figure 1, conventional high chromium stainless steel is (A) (20%Cr
-10% Ni stainless steel) and (B) (25% Cr-6
%Ni stainless steel), 3%
The alloy of the present invention (C) (69% Fe−
As seen in the curve of 25% Cr - 4% Co - 2% Cu), it has been revealed that it can withstand a pitting corrosion potential of 600 to 1300 mV in a 3% NaCl solution and exhibits high corrosion resistance. Figure 2 is a characteristic curve diagram showing the relationship between the damping capacity and the composition of the Fe- ^Cr -Co-Cu alloy of the present invention. 20)
×10 ^-3 , and this range is the range that passes the pitting corrosion test described above. In addition, the attenuation capacity Q ^-1 also exists in the range of 20.1% or less chromium.
= (5 to 40) x 10 ^-3 , but this range is excluded from the present invention because it has poor corrosion resistance and does not satisfy the two conditions of high vibration absorption and high corrosion resistance that are the objectives of the present invention. .

[Brief explanation of drawings]

Fig. 1 is a comparison curve of the pitting corrosion potential and current of the Fe-Cr-Co-Cu alloy of the present invention and conventional 25Cr-6Ni, 20Cr-10Ni stainless steel, and Fig.
FIG. 2 is a curve diagram showing the relationship between the damping capacity and composition of a Fe-Cr-Co-Cu alloy.

Claims (1)

[Claims] 1. Chromium 20.1-35%, cobalt 1.2% by weight
~19% copper, 0.01~3% copper and the balance iron, with molybdenum and tungsten 10% as subcomponents.
The following: Niobium 5% or less, aluminum, titanium 3% or less, vanadium, tantalum 2% or less, zircon, manganese 1.5% or less, phosphorus, lead, sulfur 1%
A molded body of an alloy containing 0.01 to 40% of one or more of the following in a total amount: (A) A temperature of 500°C below the melting point of the alloy for solution treatment.
(B) A step of performing cold working after cooling as described above; (C) A step of heating at a temperature of 900°C or less after the above cold working; Minutes or more
Heating for 100 hours or less, then heating at 1°C/sec to 1
By performing a slow cooling process at a rate of ℃/hour and heat treatment, we obtained an alloy with a damping capacity of Q ^-1 of 5 × 10 ^-3 or more and a corrosion-free alloy that can withstand a pitting potential of at least 300 mV or more. A manufacturing method for a highly vibration-absorbing, highly corrosion-resistant iron-based alloy.