JPH028351A - High strength and high ductile high-manganese steel having excellent irradiation characteristics - Google Patents

Abstract

PURPOSE:To manufacture the title steel by incorporating specific ratios of C, Si, Mn, P, S, Ni, Cr and N into Fe. CONSTITUTION:A high-manganese steel contg., by weight, <=0.2% C, 1 to 5% Si, 16 to 25% Mn, <=0.1 % P, <=0.1% S <= 0.05% Ni, 5 to 12% Cr and 0.1 to 0.3% N, contg., at need, one or more kinds selected from <=0.05% Ca, <=0.05% Ce, <=0.05% Mm and <=0.05% Zr and the balance Fe with inevitable impurities is prepd. By this method, the high-manganese steel having excellent strength and ductility in the temp. range of ordinary temp. or the below to -296 deg.C even if subjected to neutron irradiation can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to high strength, high ductility, high manganese steel with excellent radiation resistance. Excellent strength at temperatures below,
The present invention relates to high-strength, high-ductility high-manganese steel that is ductile, has a longer lifespan than iron, and does not generate radioactive waste, and has excellent radiation resistance properties.

[Prior art] Structures at room temperature or below, such as nuclear reactors, fusion reactors, and particle accelerators,
Austenitic stainless steel, a low-temperature steel, is used as a radioactive element storage container and as a steel that can be used as a high-strength material at room temperature (even when not irradiated), but high manganese steel ( 1) C0.2wt% or less, Si1-5wt%, Mn
16-25wt%, P 0.1wt% or less, S 0.1
wt% or less, Ni 0.05wt% or less, Cr5-12
wt%, N 0.1 to 0.3 wt%, balance Fe
The first invention is a high-strength, high-ductility, high-manganese steel with excellent radiation resistance, characterized by consisting of unavoidable impurities, (2) C0.2wt% or less, Si1-5wt%, Mn
16-25wt%, P 0.1wt% or less, S 0.1
wt% or less, Ni 0.05wt% or less, Cr5-12
wt%, N 0.1 to 0.3 wt%, Ca 0.05 wt% or less, Ce 0.05 wt%, M
High strength and high ductility with excellent radiation resistance, characterized by containing one or more selected from m 0.05wt% or less and Zr 0.05wt% or less, with the remainder consisting of Fe and unavoidable impurities. (3) G 0.2wt% or less, Si 1 to 5wt%, N
Because it contains a large amount of i, there is a problem that long-lived radioactive substances remain. In addition, this austenitic stainless steel (J) has a low yield strength at room temperature of about 25 kg/mm'.

However, although ferritic steel has excellent irradiation resistance at room temperature, there is a problem in that ductility decreases and brittle fracture occurs at low temperatures.

Therefore, there is a demand for a steel that is optimal for structures at room temperature or below, such as nuclear reactors, nuclear fusion reactors, and particle accelerators.

[Problems to be Solved by the Invention] As explained above, the present invention has been made in view of various problems with materials for conventionally used nuclear reactors, nuclear fusion reactors, particle accelerators, etc. As a result of research and consideration, we have found that it has high strength, ductility, and toughness even when exposed to radiation from nuclear fission, fusion, bremsstrahlung, etc., and has a longer lifespan than steel without producing radioactive waste. They developed a high-strength, high-ductility, high-manganese steel with excellent properties.

1. High-strength, high-ductility Mn16 with excellent radiation resistance according to the present invention
-25wt%, P 0.1wt% or less, S 0.1w1
% or less, Ni 0.05wt% or less, Cr5-12wt
%, N 0.1 to 0.3 wt%, B 0.01 wt% or less, the balance F (!) and unavoidable impurities. The third invention is a high manganese steel with high strength and high ductility, (4) C0.2wt% or more, Si1-5wt%
, Mn 16-25wt%, P 0.1w1% or less, S
0.1w1% or less, Ni 0.05wt% or less, Cr
5-12 wt%, N 0.1-03 wt%, and Ca 0.05 wt% or less, Ce 0.05 wt%, M
Contains one or more selected from m 0.05wt% or less, Zr 0.05wt% or less, and B 0.01wt% or less, with the balance consisting of Fe and inevitable impurities. This invention consists of four inventions, the fourth invention being a high-strength, high-ductility high-manganese steel with excellent radiation resistance.

The high strength, high ductility, high manganese steel with excellent radiation resistance according to the present invention will be described in detail below.

That is, in the high-strength, high-ductility high-manganese steel with excellent radiation resistance according to the present invention, the strength at room temperature is due to solid solution strengthening of Sl, but in order to suppress deterioration of ductility and toughness due to the formation of a regulating lattice, In addition to limiting the Si content, the composition is designed to make it difficult for the regulation lattice to precipitate, thereby sufficiently stabilizing the austenite. Therefore, even if the regulating grid is precipitated, it is distributed in small islands and does not significantly affect the mechanical properties.

Furthermore, although Mn and N are contained as austenite stabilizing elements, N also has an important function as a strengthening element at low temperatures. However, in Fe-Mn-N alloys, even if austenite is stable, low-temperature toughness is low, so Cr is contained in order to improve this. This Cr content does not affect the austenite phase. Sl is an element that improves the strength at room temperature, and if the content is less than 1w1%, this effect is small.
Furthermore, if the content exceeds 5 wt%, a regulating lattice is formed, causing a significant deterioration of ductility and toughness not only at low temperatures but also at room temperature. Therefore, the Si content is 1~
It is set to 5wt%.

Mn has the effect of stabilizing austenite, and N1
It is an element that can be used as a substitute for N, increasing the solid solubility limit of N and making effective use of N. If the content is less than 16 wt%, this effect will be small, and if the content is less than 25 wt%, If the content exceeds Mn, hichome will be generated, making it difficult to melt and reducing the toughness at low temperatures. Therefore, the Mn content is set to 16 to 25 wt%.

P is an element that deteriorates low-temperature toughness, and it is better to reduce it. Therefore, the P content is regulated to 0.1 wt% or less.

Like P, S is an element that deteriorates low-temperature toughness, and the less it is, the better. Therefore, the S content is regulated to 0.1 wt% or less.

α due to Cr content,
Care must be taken to prevent the appearance of second phases, such as the δ and δ phases, which cause low-temperature toughness.

However, it has been found that when neutron irradiation is performed in a nuclear reactor, austenitic alloys that originally have high ductility and toughness maintain a high level of ductility in the temperature range below room temperature, even though they become brittle due to the neutron irradiation.

In other words, based on the ingredient design for feed with a short half-life after irradiation, we developed an alloy that has high strength in the temperature range from room temperature to -290°C, is rich in ductility and toughness, and is less affected by irradiation embrittlement. I was able to do so.

First, the components and content ratios of the high-strength, high-ductility high-manganese steel with excellent radiation resistance properties according to the present invention will be explained.

C is an element that stabilizes austesite and improves low-temperature strength, but may deteriorate toughness at low temperatures. Therefore, the C content is regulated to 0.2 wt% or less.

N1 acts as an austenite stabilizing element, but since neutron irradiation creates a long-lived radioactive substance, it is preferable to reduce it as much as possible, and it is better to eliminate it substantially. Therefore, the Ni content i) is regulated to 0.05 wt% or less.

It is an element that has the effect of improving low temperature toughness in CrtJ high manganese steel, and if the content is less than 5 wt%, this effect will be small, and if it is contained in a large amount exceeding 121%, the corrosion resistance will not be improved. However, δ phase and σ phase are generated and do not harm the low temperature properties. Therefore, the Cr content is 5 to 12w.
It is assumed to be t%.

N is an element that has a strong effect on strength even at low temperatures, and also has a strong austenite stabilizing effect, and together with Mn, suppresses the formation of a restricted lattice by Si, increasing ductility and toughness. <1 I A J Orom, and the content is 0.
If the content is less than 1w1%, such excellent effects will not be achieved as expected, and if it is contained in a large amount exceeding 03w%, N hoids may be formed or the product may be exposed to high temperatures ( J filtration ability will be impaired. Therefore, the N content is 0.1 to 0.3.
Let it be wt%.

Note that CaXMg, Ce, and MmSZr are elements that remove and refine inclusions that adversely affect low-temperature toughness, and if their content exceeds 0.05 wt%, this effect disappears. Therefore, the Ca content is 0.05 wt% or less, the Mg content is 0.05 wt% or less, and the Ce content is 0.05 wt% or less.
05wt% or less, Mmm content 0.05wt% or less, Z
The r content is 0.05 wt% or less.

B suppresses grain boundary precipitation that adversely affects low-temperature toughness.

If the content exceeds 0.01 wt%, hot ductility will be impaired. Therefore, B
The content shall be 0.01 wt% or less.

[Example] An example of the high strength, high ductility, high manganese steel having excellent radiation resistance properties according to the present invention will be described.

EXAMPLES Steel having the components and proportions shown in Table 1 was melted by a conventional method, cast, and processed to obtain test pieces.

Table 2 shows the mechanical properties before and after neutron irradiation.

Further, FIG. 1 shows the temperature dependence of the elongation and tensile strength I of Alloy 1 in Table 1, and FIG. 2 shows the temperature dependence of the elongation and tensile strength of Alloy 8 in Table 1.

Comparing this Table 2 and Figures 1 and 2, it is found that 1
1jII 11 degrees ai'] or Nakahirikikakin 1 is higher,
The tensile stress (J is the same. In particular, /IK, 77! () makes alloy 8 less ductile after irradiation, and 4 causes brittle fracture "i!; It can be seen that sufficient ductility is achieved.

-I4- [Effects of the Invention] As explained above, the high-strength, high-ductility, high-manganese steel with excellent radiation resistance according to the present invention has a two-legged structure, so it is stable at room temperature when irradiated with neutrons. It has excellent strength and ductility in the range of ~296°C, and even when not irradiated, low lA7 is used as a material.
In addition, it is easy to dispose of after use because it does not generate long-lived radioactive substances when irradiated with neutrons. It is austenitic stainless steel, and therefore places where there is a possibility of neutron irradiation, or places where there is a possibility of exposure to other radiation, such as low-temperature structures such as nuclear fusion, vino of radiation facilities, nearby structures, etc. It is a high-strength, high-ductility sea bream that can be applied to

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between temperature and tensile strength of a high-strength, high-ductility high-manganese steel (alloy 1 in Table 1) with excellent radiation resistance properties according to the present invention, and Figure 2 is a diagram showing the relationship between temperature and tensile strength of a comparative steel (alloy 1 in Table 1). A diagram showing the relationship between temperature and tensile strength of alloy 8) Patent applicant Yutaka Kawashima and two other attorneys and patent attorney Yoshihisa Maruki

Claims (4)

[Claims] (1) C0.2wt% or less, Si1-5wt%, Mn1
6-25wt%, P0.1wt% or less, S0.1wt%
Below, Ni0.05wt% or less, Cr5-12wt%,
A high-strength, high-ductility, high-manganese steel with excellent radiation resistance, containing 0.1 to 0.3 wt% of N, with the remainder consisting of Fe and unavoidable impurities. (2) C0.2wt% or less, Si1-5wt%, Mn1
6-25wt%, P0.1wt% or less, S0.1wt%
Below, Ni0.05wt% or less, Cr5-12wt%,
Contains N0.1-0.3wt%, and also contains Ca0.05wt% or less, Ce0.05wt%, Mm0
．． A high-strength, high-ductility, high-manganese steel with excellent radiation resistance, characterized by containing one or more selected from Zr.05 wt% or less and Zr. . (3) C0.2wt% or less, Si1-5wt%, Mn1
6-25wt%, P0.1wt% or less, S0.1wt%
Below, Ni0.05wt% or less, Cr5-12wt%,
A high-strength, high-ductility high-manganese steel with excellent radiation resistance, characterized in that it contains 0.1 to 0.3 wt% of N, and 0.01 wt% or less of B, with the balance consisting of Fe and unavoidable impurities. (4) C0.2wt% or less, Si1-5wt%, Mn1
6-25wt%, P0.1wt% or less, S0.1wt%
Below, Ni0.05wt% or less, Cr5-12wt%,
Contains N0.1-0.3wt%, and also contains Ca0.05wt% or less, Ce0.05wt%, Mm0
．． 05 wt% or less, Zr 0.05 wt% or less, and B0.01 wt% or less, with the balance consisting of Fe and inevitable impurities. High-strength, high-ductility high-manganese steel with excellent properties.