JP2007084882A - Low work-hardening type iron alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron alloy having high yield strength and tensile strength, extremely low work-hardening rate and excellent ductility, corrosion resistance and oxidation resistance. <P>SOLUTION: The low work-hardening iron alloy has a composition which is in a region A enclosed with lines connecting four points in a diagram (shown in a figure) of Cr equivalent represented by [Cr equivalent(%)=(Cr%+1.21Mo%+0.48Si%+2.48Al%)] (by mass, the same applies to the following) versus Ni equivalent represented by [Ni equivalent(%)=(Ni%+0.11Mn%-0.0086(Mn%)<SP>2</SP>+24.5C%)] and has the balance Fe with inevitable impurities. This alloy is a ferromagnetic material having ≥10 emu/g saturation magnetization and has <16 MPa/% work-hardening rate at the application of 10% strain in the tensile stress-strain curve. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

   The present invention relates to an iron alloy having high strength and a very low work hardening rate (slope of tensile stress-strain curve).

  Alloys based on iron have a high amount of iron on the earth, are easy to manufacture (established manufacturing methods), have a relatively high strength (steel etc.), and are corrosion resistant (stainless steel, Alloy steel) for various fields such as general structural materials, building materials, railcars and automobile bodies and frame materials, rail materials, marine materials, corrosion resistant materials, pipeline materials for oil, bridge materials, etc. in use.

Generally, an austenitic phase (γ phase (fcc structure)) iron alloy typified by austenitic stainless steel or the like can be strengthened by utilizing the formation of work-induced martensite by cold working or the like. On the other hand, since work hardening occurs during a process of processing a product having a complicated shape, it is necessary to repeat the process while softening with intermediate annealing.
For this reason, several documents have been disclosed for iron alloys with low work hardening properties (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). According to these patent documents, low work hardenability is obtained by using the austenite stabilizing elements Ni, Cu, and Mn and suppressing the work-induced martensitic transformation.

However, these iron alloys are usually austenite single phase and are paramagnetic, but their yield strength (0.2% proof stress) and tensile strength are as low as about 300 MPa and 700 MPa or less, respectively, and work hardenability. Is not low enough for practical use.
In addition, as a known steel type having low work hardenability, there is SUS305 or the like, but the strength is low as in the case of the above alloy, and the low work hardenability is not sufficient.
JP-A-2-141556 JP 5-117815 JP 2005-154890 A

  An object of the present invention is to provide an iron alloy that has high yield strength and tensile strength, has an extremely low work hardening rate, and is rich in ductility, corrosion resistance, and oxidation resistance.

The present inventors have improved iron-manganese-aluminum materials and proposed by Hull et al. (Refer to Welding J. 52 (5) (1973) 193s, Welding research supplement). On the Cr equivalent vs. Ni equivalent diagram, when the work hardening rate line was investigated, the work hardening rate could be greatly reduced without reducing the strength and ductility in a certain region, and the alloys were ferromagnetic. I got the knowledge.
Based on this finding, the following invention is provided.

As 1), Mn: 10.0 to 45.0 mass%, Al: 5.0 to 15.0 mass%, C: 0.5 to 2.0 mass%, Si: 0.01 to 5.0 Containing mass%, Cr: 0.01-10.0 mass%, Ni: 0.001-15 mass%, Cr equivalent (mass%) = (Cr mass% + 1.21 Mo mass% + 0.48 Si mass% + 2 .48 Al mass%) and Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%)) ) (Cr equivalent: 22.0 mass%, Ni equivalent: 48 mass%), (Cr equivalent: 10 mass%, Ni equivalent: 10 mass%), (Cr equivalent: 38 mass%, Ni equivalent: 11 mass%) %), (Cr equivalent: 45 mass%, Ni equivalent: 41 mass%) A low-work-hardening iron alloy consisting of the remainder Fe and inevitable impurities in A, a ferromagnetic material having a saturation magnetization of 10 emu / g or more, and work hardening when 10% strain is applied in the tensile stress-strain curve A low work-hardened iron alloy having a rate of less than 16 MPa /% is provided.

As 2), Mn: 15.0 to 40.0 mass%, Al: 8.0 to 15.0 mass%, C: 0.5 to 2.0 mass%, Si: 0.01 to 5.0 Containing mass%, Cr: 5.0 to 10.0 mass%, Ni: 0.01 to 15 mass%, Cr equivalent (mass%) = (Cr mass% + 1.21 Mo mass% + 0.48 Si mass% + 2 .48 Al mass%) and Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%)) ) (Cr: 25 mass%, Ni: 48 mass%), (Cr: 24.2 mass%, Ni: 10 mass%), (Cr: 38 mass%, Ni: 11 mass%), (Cr: 45% by mass, Ni: 41% by mass) in the region B surrounded by four points, the remaining Fe and inevitable impurities A low work-hardening iron alloy comprising a ferromagnetic material having a saturation magnetization of 15 emu / g or more and having a work hardening rate of less than 10 MPa /% when 10% strain is applied in a tensile stress-strain curve. Provide work hardened iron alloys.

As the third, there is provided a low work hardening iron alloy according to 1) or 2), which is a ferromagnetic material containing a perovskite phase (κ phase) having a size of 1 μm or less in a matrix.
As 4), B: 0.001 to 1.5% by mass, N: 0.001 to 1.5% by mass, and Be, Mg, Ti, each added amount of 0.01 to 5.0% by mass, A low work hardening iron alloy according to any one of 1) to 3), which further contains one or more elements selected from V, Co, Cu, Nb, Mo, Ta, and W.

  By making the iron alloy of the present invention ferromagnetization, the work hardening rate when a 10% strain is applied in the tensile stress-strain curve can be reduced to less than 16 MPa /%, and the Young's modulus is 100 GPa or more and 0.2%. It has a yield strength of 500 MPa or more and a tensile strength of 800 MPa or more, and has an effect that a material having low work curability and excellent strength and ductility can be obtained.

The low work hardening iron alloy of the present invention has Mn: 10.0 to 45.0 mass%, Al: 5.0 to 15.0 mass%, C: 0.5 to 2.0 mass%, Si: 0.00. 01-5.0 mass%, Cr: 0.01-10.0 mass%, Ni: 0.01-15 mass% are contained, Cr equivalent (mass%) = (Cr mass% + 1.21 Mo mass% + 0 .48Si mass% + 2.48Al mass%) and Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%) In the equivalent diagram (FIG. 1), (Cr equivalent: 22.0 mass%, Ni equivalent: 48 mass%), (Cr equivalent: 10 mass%, Ni equivalent: 10 mass%), (Cr equivalent: 38 mass%, (Ni equivalent: 11% by mass), (Cr equivalent: 45% by mass, Ni equivalent: 41% by mass) Is a low work-hardened iron alloy consisting of the remaining Fe and inevitable impurities, and becomes a ferromagnetic material having a saturation magnetization of 10 emu / g or more, and when a 10% strain is applied in the tensile stress-strain curve. The work hardening rate can be suppressed to less than 16 MPa /%.
As for the Cr equivalent, naturally, Cr can be replaced with Mo, Si, and Al within the range of (Cr mass% + 1.21 Mo mass% + 0.48 Si mass% + 2.48 Al mass%). Similarly, regarding Ni equivalent, Ni can be replaced with Mn and C within the range of (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%).

In particular, Mn: 15.0 to 40.0 mass%, Al: 8.0 to 15.0 mass%, C: 0.5 to 2.0 mass%, Si: 0.01 to 5.0 mass%, Cr: 5.0 to 10.0 mass%, Ni: 0.01 to 15 mass%, Cr equivalent (mass%) = (Cr mass% + 1.21 Mo mass% + 0.48 Si mass% + 2.48 Al mass) %) And Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%)) (Cr: 25 mass%, Ni: 48 mass%), (Cr: 24.2 mass%, Ni: 10 mass%), (Cr: 38 mass%, Ni: 11 mass%), (Cr: 45 mass%) , Ni: 41% by mass) in a region B surrounded by four points, a strong magnetization having a saturation magnetization of 15 emu / g or more. It becomes sex body, tensile stress - work hardening rate during 10% strain added in the strain curve can be suppressed to less than 10 MPa /%.

The iron alloy having the above composition can be a ferromagnetic material containing a perovskite phase (κ phase) having a size of 1 μm or less in the matrix, and becomes a low work hardening iron alloy having high yield strength and tensile strength.
The reason why Mn is 10.0 to 45.0% by mass is that if the amount is less than 10.0% by mass, a γ phase having an fcc structure cannot be obtained, and if it exceeds 45.0% by mass, sufficient strength cannot be obtained. It is. In particular, Mn: 15.0 to 40.0% by mass is desirable. Thereby, the tensile strength can be further improved.

The reason for Al: 5.0-15.0% by mass is that if it is less than 5.0% by mass, it cannot be ferromagnetized, so a low work hardening rate cannot be obtained, and if it exceeds 15.0% by mass, a large amount This is because an α phase (bcc structure) and a coarse κ phase are precipitated and rapidly embrittled. In particular, Al: 8.0-15.0 mass% is desirable. Thereby, intensity | strength can be improved further.
The reason for C: 0.5 to 2.0% by mass is that if it is less than 0.5% by mass, a large amount of α phase is precipitated and becomes brittle, and if it exceeds 2.0% by mass, M ₃ C (M: This is because carbides such as Fe, Mn, Cr, etc. are precipitated.

The reason for Si: 0.01 to 5.0% by mass is that high yield strength cannot be obtained if it is less than 0.01% by mass, and a large amount of α phase precipitates and becomes brittle if it is 5.0% by mass or more. It is.
The reason why Cr is 0.01 to 10.0% by mass is that if it is less than 0.01% by mass, an alloy excellent in corrosion resistance and oxidation resistance cannot be obtained, and if it exceeds 10.0% by mass, Cr carbide and σ phase are obtained. Intermetallic compounds such as appear. In particular, Cr: 5.0-10.0 mass% is desirable. Thereby, corrosion resistance can further be improved.
The reason why Ni is 0.001 to 15.0% by mass is that if it is less than 0.001% by mass, high ductility cannot be obtained, and if it exceeds 15% by mass, a low work hardening rate cannot be obtained. is there. In order to have a ductility effect by adding Ni, it is desirable that the lower limit value of Ni addition is particularly 0.01% by weight.

As is clear from FIG. 1, in the Cr equivalent to Ni equivalent diagram, (Cr equivalent: 22.0 mass%, Ni equivalent: 48 mass%), (Cr equivalent: 10 mass%, Ni equivalent: 10 mass%), The reason why the region A is surrounded by four points (Cr equivalent: 38% by mass, Ni equivalent: 11% by mass) and (Cr equivalent: 45% by mass, Ni equivalent: 41% by mass) is that the work hardening rate is 16 MPa / This is to suppress the content to less than%.
Further, as is apparent from FIG. 2, in the Cr equivalent to Ni equivalent diagram, (Cr: 25 mass%, Ni: 48 mass%), (Cr: 24.2 mass%, Ni: 10 mass%), (Cr : 38% by mass, Ni: 11% by mass), and (Cr: 45% by mass, Ni: 41% by mass), the reason why the region B is surrounded by four points is to suppress the work hardening rate to less than 10 MPa /%. is there. Thereby, the work hardening rate can be further reduced.

The low specific gravity iron alloy of the present invention further comprises B: 0.001 to 1.5% by mass, N: 0.001 to 1.5% by mass, and 0.01 to 5.0% by mass of Be, Mg, Ti, respectively. , V, Co, Cu, Nb, Mo, Ta, or W can be added with one or more elements selected from elements.
B: 0.001 to 1.5% by mass The reason why the content is less than 0.001% by mass is that a fine grain structure cannot be obtained even in the cast structure and the forged structure. This is because it becomes brittle by precipitation of the like.
The reason for N: 0.001 to 1.5% by mass is that sufficient specific strength cannot be obtained if it is less than 0.01% by mass, and if it exceeds 1.5% by mass, embrittlement occurs due to precipitation of nitride or the like. Because it does. In the above composition range, a fine crystal grain structure is obtained, and an alloy having excellent mechanical properties is obtained.

Addition of Be or Mg is effective in increasing strength, addition of Ti is effective in preventing intergranular corrosion, addition of V is effective in improving wear resistance, and addition of Co is effective in stabilizing the γ phase. This is because the addition of Cu or Mo is effective for improving the corrosion resistance, the addition of Mo, Nb, and Ta is effective for improving the intergranular corrosion resistance, and the addition of W is effective for precipitation hardening.
These can be added alone or in combination. Moreover, there exists a problem which does not have the effect of addition if it is less than 0.01 mass%, and becomes embrittled when it exceeds 5.0 mass% to make these into the range of 0.01-5.0 mass%. Therefore, the upper limit is 5.0% by mass. These are added as subcomponents in order to further improve the characteristics of the iron alloy of the present invention, and are not essential components.

As described above, the low work hardening rate iron alloy of the present invention is a ferromagnetic material having a saturation magnetization of 10 emu / g or more, and the work hardening rate when applying 10% strain in the tensile stress-strain curve is 16 MPa / Is a ferromagnetic material having a saturation magnetization of 15 emu / g or more by controlling the Ni equivalent and Cr equivalent, and the work hardening rate when a 10% strain is applied in the tensile stress-strain curve. The alloy has a low work hardening rate of less than 10 MPa /%.
In particular, in the low work-hardening iron alloy of the present invention, a work hardening rate is less than 10 MPa /%, a yield strength is 700 MPa or more, and a tensile strength is 900 MPa or more by using a ferromagnetic material in which a fine κ phase is precipitated. It can be.

As a manufacturing method of this invention alloy, first, Mn: 10.0-45.0 mass%, Al: 5.0-15.0 mass%, C: 0.5-2.0 mass%, Si: 0.00. Components are adjusted within a composition range of 01 to 5.0 mass%, Cr: 0.01 to 10.0 mass%, Ni: 0.01 to 15 mass%, and the balance Fe.
Moreover, as needed, B, N (0.001-1.5 mass% each) and Be, Mg, Ti, V, Co, Cu, Nb, Mo, Ta, and W (each 0.01-5. A predetermined amount of one or two or more elements selected from the group consisting of 0% by mass) is added to appropriately adjust the raw material components.
When adding B, N and Be, Mg, Ti, V, Co, Cu, Nb, Mo, Ta and W, an alloy such as pure element simple substance, ferroboron, ferrotantalum, ferroniobium, etc. is appropriately adjusted to a predetermined amount. It is added or dissolved by dissolution in a nitrogen atmosphere.

Next, this is melted by using an arc melting furnace or a high-frequency melting furnace, which is used as a casting ingot, and further hot forging or hot rolling and subsequent cold rolling at a temperature of 800 ° C. to 1300 ° C. Or it is made into a product through processing steps such as wire drawing. Moreover, as needed, it heat-processes at the temperature of 700 degreeC-1300 degreeC, and quenches, furnace cools, or air cools and manufactures. Furthermore, if necessary, the strength can be adjusted by performing aging or processing at a temperature of 200 ° C. to 1000 ° C. after the heat treatment.
The material thus obtained can have a γ single phase, a γ + α (bcc structure) 2 phase, a γ + κ2 phase, and a γ + α + κ3 phase structure by selecting the chemical composition and processing conditions of the alloy.
The structure applicable in the present invention is an iron alloy having a structure including a γ + α (bcc structure) two-phase structure and a fine κ phase, and particularly in an alloy having a structure containing a fine κ phase, extremely high strength and tensile strength. And the iron alloy of this invention provided with very low work-hardening property is obtained.
In order to obtain such a microstructure of κ phase, it is important to control the cooling rate after the heat treatment, and manufacturing processes such as quenching in water, quenching in oil, air cooling, and furnace cooling are employed depending on the alloy composition.

In particular, in order to precipitate a fine κ phase, an ingot obtained by melting is hot-worked at a temperature of 800 ° C. to 1300 ° C., and then the fine κ phase is precipitated in the cooling process. it can. Specifically, for example, after casting a cast ingot or the cast ingot, or after further cold working as necessary, at a temperature of 700 ° C. to 1300 ° C. for 0.1 minutes or more Heat treatment is performed, and fine κ phase is precipitated by cooling such as quenching in water, quenching in oil, air cooling, furnace cooling and the like. In this case, the cooling rate is preferably 10 to 1000 ° C./second.
Moreover, after hot rolling the cast ingot or the cast ingot or further cold-working it as necessary, it is once converted into a γ single phase by heat treatment, and then 1 in a temperature range of 200 ° C to 1000 ° C. A fine κ phase can also be precipitated by aging for more than a minute. In the present invention, if fine κ phase precipitation can be achieved, the production process is not particularly limited, and necessary processing, heat treatment and cooling can be performed.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. That is, other examples, modes, modifications, and the like within the scope of the technical idea of the present invention are naturally included.
(Example 1-23)
In the range of the iron alloy of the present invention, the alloy composition of Example 1-23 shown in Table 1 was melted using a high frequency melting furnace, and this was made into a casting ingot. Next, an alloy sample was produced through a manufacturing process of hot rolling at a temperature of 1100 ° C., heat treatment for 10 minutes at a temperature of 900 to 1100 ° C., and quenching in water or air cooling.

Table 2 shows the Young's modulus (GPa), 0.2% yield strength (MPa), work hardening rate (MPa /%), tensile strength (MPa), tensile elongation (%), and saturation of the iron alloys of Examples 1 to 23. Magnetization (emu / g) and constituent phases are shown.
Each alloy shown in Example 1-23 was a ferromagnetic material with a saturation magnetization of 10 emu / g or more, and the work hardening rate when 10% tensile strain was applied was 16 (MPa /%) or less.
Examples 1, 2, 5 and 9 have a γ + α phase and are ferromagnetic. A representative example (Example 2) of a tissue containing this γ + α phase is shown in FIG. In FIG. 3, the granular or string-like structure scattered in the γ phase is the α phase, and even a relatively coarse crystal having a string length of about 200 μm does not become brittle. The curing rate is reduced and good ductility is exhibited.
The other examples, ie, Examples 3, 4, 6, 7, and 10-23, have fine κ phase, ie, γ phase + α phase + κ phase or γ phase + κ phase structure, and are similarly strong. It is a magnetic material. In both cases, the work hardening rate is lowered and ductility is exhibited.
The work hardening rate of the present iron alloy tends to decrease as the Al concentration increases. In particular, in the alloy existing in the region B in the Cr equivalent vs. Ni equivalent diagram (FIG. 2), 10 (MPa /%) Less than and very small.

In FIG. 4, an example of the stress-strain curve obtained by the tension test of Example 3, 9-15 is shown. In particular, in Examples 11 and 13, it can be seen that almost no work hardening has occurred.
FIG. 5 shows the work hardening rate at the time of 10% tensile strain addition obtained in the alloys of Examples 1 to 23 on the Cr equivalent vs. Ni equivalent diagram and at the time of 10% tensile strain addition in the alloys of Comparative Examples 1 to 16 described later. The work hardening rate was expressed.
All of the example alloys in the region A have a work hardening rate of less than 16 (MPa /%). In particular, all of the example alloys in the region B have a work hardening rate of 10 (MPa /%). It turns out that it is less than.
It can be seen that the iron alloy of the present invention can change Young's modulus, yield strength, tensile strength, elongation, and saturation magnetization in various ways by adjusting the amount of added components.

FIG. 6 shows the γ + κ2 phase structure in which the fine κ phase obtained in Example 13 is precipitated. This organization, L1 ₂ obtained from spots transmission electron microscope (TEM) is a dark-field image. It shines white and dice-like precipitate to the matrix, which is a κ-phase having an L1 ₂ structure, the matrix with respect, it can be seen that has a constant crystal orientation.
As shown in FIG. 6, the size of the kappa precipitate phase is very fine, 100 nm or less. In particular, the present iron alloy having such a structure is a ferromagnetic material, has high proof stress, high strength, and high ductility, and has an extremely low work hardening rate. The fine κ phase as shown in FIG. 6 is generated particularly in the cooling process after heat treatment (by water quenching, air cooling, furnace cooling, etc.).

(Comparative Example 1-16)
Comparative Example 1-16 is an iron alloy that departs from the present invention, and an iron alloy was manufactured by using the alloy components of Comparative Example 1-16 shown in Table 3 through the same manufacturing steps as in the examples.
As for Comparative Example 1-16, in Table 4, as in Examples, the Young's modulus (GPa), 0.2% yield strength (MPa), work hardening rate (MPa /%), and tensile strength (MPa) of the comparative example alloy , Tensile elongation (%), saturation magnetization (emu / g) and constituent phases.

Comparative Examples 5, 6 and 16 are austenite (γ) single-phase alloys, exhibit paramagnetism, and have a large work hardening rate of 16 (MPa /%) or more.
Comparative Examples 3 and 4 are ferromagnets due to the presence of the α phase, but deviate from the composition range of the alloy of the present invention, and the work hardening rate is as large as 16 (MPa /%) or more.
The iron alloys of Comparative Examples 1, 2, and 7 to 15 exhibit ferromagnetism due to the presence of the α phase and the coarse κ phase, but deviate from the composition range of the alloy of the present invention. Moreover, due to the precipitation of coarse κ phase larger than 1 μm size, the ductility was poor and the tensile elongation was 10% or less in all cases.

In FIG. 7, an example of the stress-strain curve obtained by the tension test of Comparative Examples 3-6 is shown. In any of the comparative examples, it can be seen that rapid work hardening has occurred.
As shown in FIG. 5, the comparative examples outside the category of region A and region B in the Cr equivalent vs. Ni equivalent diagram of the present invention both have a work hardening rate of 16 (MPa /%) when 10% tensile strain is applied. ) Greater than that. In addition, the tensile elongation is 10% or less and the ductility is poor.
On the other hand, Comparative Example 8 has Cr equivalent and Ni equivalent in the component range of the present invention, but does not contain Cr at all, and a coarse κ phase is precipitated, so that the tensile elongation is 0.25%. It was extremely bad. This is because the material of Comparative Example 8 does not contain any Cr, so the κ phase exists as a stable phase at the heat treatment temperature (1100 ° C.), and the size of the κ phase is easily coarsened. .
FIG. 8 shows the γ + κ2 phase structure containing the coarse κ phase obtained in Comparative Example 8. This structure was observed with an optical microscope. The matrix is a γ phase, and it can be seen that a coarse κ phase is precipitated therein. Since such a coarse κ phase already exists at a heat treatment temperature of 1100 ° C., its size is large, which causes a rapid decrease in material. The iron alloy having this coarse κ phase is very brittle and cannot achieve a tensile elongation of 10% or more.

  Since the iron alloy of the present invention can reduce the work hardening rate to less than 16 (MPa /%), it is excellent in formability and can produce various members at low cost. In addition, since it has a high strength of 0.2% proof stress 500 MPa or more and tensile strength 800 MPa or more, it is a structural material, a vibration isolating material, a railway vehicle or automobile body or frame material, a rail material, a ship material, a corrosion resistant material, petroleum, etc. It can be used in various fields such as pipeline materials, bridge materials, and golf equipment.

4 points (Cr: 22 mass%, Ni: 48 mass%), (Cr: 10 mass%, Ni: 10 mass%), (Cr: 38 mass%, Ni: 11 mass%), (Cr: 45 mass%) , Ni: 41 mass%) is a Cr equivalent vs. Ni equivalent diagram showing a region A surrounded by A). 4 points (Cr: 25 mass%, Ni: 48 mass%), (Cr: 24.2 mass%, Ni: 10 mass%), (Cr: 38 mass%, Ni: 11 mass%), (Cr: 45 It is Cr equivalent vs. Ni equivalent figure which shows the area | region B enclosed by the mass% and Ni: 41 mass%). It is a microscope picture of the structure of γ + α phase. It is a figure which shows the stress-strain curve of Example 3, 9-15. It is the figure which showed the work hardening rate value of the Example and the comparative example, the equal work hardening rate line, and the area | regions A and B. FIG. It is a microscope picture which shows the (gamma) + (kappa) 2 phase structure | tissue containing the fine (kappa) phase obtained in Example 13. FIG. It is a figure which shows the stress-strain curve of Comparative Examples 3-6. 6 is a micrograph showing a γ + κ2 phase structure containing a coarse κ phase obtained in Comparative Example 8.

Claims (4)

Mn: 10.0-45.0 mass%, Al: 5.0-15.0 mass%, C: 0.5-2.0 mass%, Si: 0.01-5.0 mass%, Cr: 0.01 to 10.0% by mass, Ni: 0.001 to 15% by mass, Cr equivalent (% by mass) = (Cr mass% + 1.21Mo mass% + 0.48Si mass% + 2.48Al mass%) And Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%) Cr equivalent vs. Ni equivalent diagram (FIG. 1), Equivalent: 22.0 mass%, Ni equivalent: 48 mass%), (Cr equivalent: 10 mass%, Ni equivalent: 10 mass%), (Cr equivalent: 38 mass%, Ni equivalent: 11 mass%), (Cr Equivalent: 45% by mass, Ni equivalent: 41% by mass) in the region A surrounded by four points, and the rest A low work hardening iron alloy consisting e and unavoidable impurities, 10 emu / g and a ferromagnetic material having a higher saturation magnetization, the tensile stress - 10% in the strain curve distortion applying during the work hardening rate of 16 MPa /% Low work hardening iron alloy characterized by being less than. Mn: 15.0-40.0% by mass, Al: 8.0-15.0% by mass, C: 0.5-2.0% by mass, Si: 0.01-5.0% by mass, Cr: 5.0 to 10.0 mass%, Ni: 0.01 to 15 mass%, Cr equivalent (mass%) = (Cr mass% + 1.21 Mo mass% + 0.48Si mass% + 2.48 Al mass%) And Ni equivalent (mass%) = (Ni mass% + 0.11 Mn mass% −0.0086 (Mn mass%) ² +24.5 C mass%) : 25 mass%, Ni: 48 mass%), (Cr: 24.2 mass%, Ni: 10 mass%), (Cr: 38 mass%, Ni: 11 mass%), (Cr: 45 mass%, Ni : 41 mass%) in the region B surrounded by four points, and low processing consisting of the remaining Fe and inevitable impurities It is a ferrous alloy and a ferromagnetic material having a saturation magnetization of 15 emu / g or more, and has a work hardening rate of less than 10 MPa /% when 10% strain is added in a tensile stress-strain curve. Low work hardening iron alloy.   The low work-hardening iron alloy according to claim 1 or 2, which is a ferromagnetic material containing a perovskite phase (κ phase) having a size of 1 µm or less in a matrix. B: 0.001 to 1.5% by mass, N: 0.001 to 1.5% by mass, and Be, Mg, Ti, V, Co, and Cu, each addition amount being 0.01 to 5.0% by mass The low work hardening iron alloy according to any one of claims 1 to 3, further comprising one or more elements selected from N, Nb, Mo, Ta, and W.

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