JPS6299445A - Manufacture of aluminum alloy excellent in thermal neutron absorption property and in strength at high temperature - Google Patents

Abstract

PURPOSE:To improve thermal neutron absorption property and strength at high temp. by adding specific amounts of Gd, Mg, elements improving strength at ordinary temp., toughness, and corrosion resistance, and elements having thermal neutron absorption property to Al, by regulating the size of ingot crystalline grain to a specific value or below, and by applying soaking treatment under specific conditions. CONSTITUTION:An Al alloy ingot has a composition consisting of, by weight, 0.2-30% Gd, 0.5-6% Mg, 1 or >=2 kinds among <1% Mn, <0.3% Zr, <0.3% V, <3% B, <3% Li, <1% Si, <1% Zn, <1% Cu, <2% Ni, and <1% Ti, and the balance Al with inevitable impurities. The grain size of the above Al alloy ingot is regulated to <=5mm, to which soaking treatment is applied at 400-550 deg.C for >=2hr.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention is directed to a method for producing an aluminum alloy with excellent thermal neutron absorption ability and high-temperature strength. This paper relates to a method for producing aluminum alloys with excellent thermal neutron absorption ability and high-temperature strength, which are used in

[Prior Art 1] In general, in facilities that use nuclear fuel materials such as various nuclear reactor facilities, reprocessing facilities, and nuclear fuel material storage facilities, as well as facilities that transport nuclear fuel materials, the basic requirements for nuclear fuel materials are “
"Ensuring subcriticality".

By the way, fissile materials such as 235-U and 239-Pu tend to undergo nuclear fission in response to thermal neutrons (~several eV), so it is necessary to absorb them and lower the thermal neutron flux to increase subcriticality. These facilities and equipment often use metal materials with high thermal neutron absorption capacity.

In particular, in recent years, commercial nuclear reactors have become increasingly highly enriched due to the higher burnup of nuclear fuel, and research reactors are using nuclear fuel with much higher enrichment than this. Containers (hereinafter simply referred to as baskets) are used to transport and store spent nuclear fuel.

), metal materials with even higher thermal neutron absorption ability than before are needed.

In addition, the basket is exposed to even higher temperatures due to the decay heat of the spent nuclear fuel, and
It is said that the temperature reaches as high as 0''C, and for this reason, there is a need for metal materials with high high-temperature strength.

As such a metal material, Boral (B
Rooks & Perkins product name), B, C and C
There are aluminum alloys in which a mixed sintered material of U is cast, aluminum alloys containing B, etc., but there is a demand for aluminum alloys with even better thermal neutron absorption ability.

[Problems to be Solved by the Invention] As explained above, the present invention is based on the conventional materials having thermal neutron absorption ability and the aluminum alloy and thermal neutron absorption which the present inventor has previously proposed and has filed an application for. However, as a result of research on aluminum alloys, which have particularly excellent high-temperature strength, we found that they have significantly superior high-temperature strength and thermal neutron absorption ability, and have excellent castability, stretchability, and moldability. They developed a method for producing an aluminum alloy with extremely good thermal neutron absorption ability and high-temperature strength.

Means for Solving Problem E 1 The method of manufacturing an aluminum alloy with excellent thermal neutron absorption ability according to the present invention is characterized by: Gd 0.2-30%, Mg 0.5-6+ut% furthermore, Mn 1u+j% or less, Cr 0.3u+t% or less, Z
r O8:3u+1%, V 0.3wt% or less, B 3
u+t% or less, Li5ult% or less, Si] u+t% or less, Zn], u+t% or less, Cu 1ust% or less,
The crystal grain size of an aluminum alloy ingot containing one or more selected from Ni2wt% or less and Ti1% or less, and the balance A1 and unavoidable impurities, is 5cm or less, and 4
The purpose is to perform soaking treatment at a temperature of 00 to 550°C for 2 hours or more.

The method for producing an aluminum alloy with excellent thermal neutron absorption ability and high-temperature strength according to the present invention will be described in detail below.

First, the components and component ratios of the aluminum alloy used in the method for producing an aluminum alloy with excellent thermal neutron absorption ability and high-temperature strength according to the present invention will be explained.

Gd is an important element that provides thermal neutron absorption ability.
If the content is less than 0.2u+L%, the effect will be small and it will be smaller than conventional materials, and if the content exceeds 30υ+L%, the casting layer 1. This makes it difficult to produce an ingot, and furthermore, the molding processability by rolling, extrusion, etc. becomes poor, making it difficult to form into a product. Therefore, the Gd content is 0.
The content is 2 to 30 wt%.

Mg is an effective element for imparting not only room-temperature strength but also high-temperature strength.If the content is less than 0.5u+t%, the effect is small, and if the content exceeds 6u+t%, it will cause rolling problems. Stretching workability such as extrusion becomes poor, corrosion resistance deteriorates, and weldability also becomes poor. Therefore, Mg
The content is 0.5-6u+t%.

Mn, Cr, Zr, ■ are elements that improve room-temperature strength, toughness, and corrosion resistance, and also have the effect of improving high-temperature strength 1), with a content of Mn 1wt% and Cr 0.3wt.
%, Zr 013u+t%, and V 0.3wt%, no improvement in effectiveness can be expected, and giant compounds that deteriorate toughness and corrosion resistance are likely to be produced. but,
Since Cr is activated, it is better not to include it unless there is an immediate need to include it. Therefore, the Mn content is 1 wt% or less, the Cr content is 0.3% or less, and the Zr content is 0.
3wt% or less, (2) content is 0.3u+t% or less.

B is an element that has thermal neutron absorption ability like Gd,
By including it together with Gd, the crystallized compound of A13Gd present in the Al-Gd alloy is finely and uniformly dispersed, and the uneven distribution of thermal neutron absorption ability is reduced, and when the content exceeds 31%, castability is improved. becomes worse, and high-temperature strength decreases. Therefore, the B content is set to 3u+t% or less.

Like B, Li is an element that has thermal neutron absorption ability,
In addition, it improves the room temperature strength of the Al-Gd alloy, and when the content exceeds 3u+L%, it improves castability and rolling properties.
Forming processability such as extrusion is significantly deteriorated, elongation is significantly reduced, ductility is deteriorated, and performance as a structural material is lost. Therefore, the Li-containing goldstone should be 3u+t% or less.

Si, Zn, and Cu are elements that improve room-temperature strength and high-temperature strength, and if the Si content exceeds ]u+I%, the stretching processability in rolling, extrusion, etc. will deteriorate, and Zn
If the content exceeds 1u+L% and the Cu content exceeds but%, corrosion resistance such as general corrosion resistance and stress corrosion cracking resistance will deteriorate. Therefore, the Si content is 1ul1% or less, the Zn content is ]u+t% or less, and the Cu content is 1wt%.
The following shall apply.

Ni is an element that improves high temperature strength, and the content is 2u
If the content exceeds +t%, the effect will be saturated and the stretchability in rolling, extrusion, etc. and corrosion resistance will deteriorate. Therefore, the Ni content is set to 2u+t% or less.

Ti is an element that refines the structure of the la mass, prevents casting cracks, and improves high-temperature strength.
When the content exceeds It%, this effect is saturated,
In addition, the crystallized compound of A I 3T i increases and the toughness deteriorates. Therefore, the Ti content is set to 11% or less.

In addition to the components explained above, Fe is an impurity.
If the content of elements in the pond is 0.5 u+t% or less, the properties of thermal neutron absorption capacity and high temperature strength will not be affected.

Next, a method for manufacturing an aluminum alloy having excellent thermal neutron absorption ability and high-temperature strength according to the present invention will be explained.

511111 is an equiaxed product that is a crystal grain of an aluminum alloy ingot with the above-mentioned components and component ratios.
If it is less than 1, the crystallized compound will not be uniformly dispersed, the high-temperature strength will be low, and the castability and 7-stretching properties such as rolling and extrusion will deteriorate.

Soaking treatment is carried out at temperatures exceeding 400°C and 71 degrees Celsius, and high temperature strength decreases at temperatures exceeding 550°C.If soaking time is less than 2 hours, the effect is lost, and stretching processes such as rolling, extrusion, etc. Sexuality begins to deteriorate.

Therefore, the grain size of the aluminum alloy ingot is 5m.
+n or less, and the soaking treatment is carried out at a temperature of 400 to 550°C for 2 hours or more.

[Example 1] An example will be described regarding the method for producing an aluminum alloy having excellent thermal neutron absorption ability and high-temperature strength according to the present invention.

Example 1 An aluminum alloy having the components and proportions shown in Table 1 was melted and cast by a conventional method, and the crystal grain size was 50 mm thick. After soaking an aluminum alloy ingot of ++ua at 450° C. for 12 hours, it was hot rolled into a plate material with a thickness of S+n+n.

Next, this plate material was annealed at 350"C for 2 hours to obtain a test material.

These test materials were investigated for thermal neutron absorption capacity and high temperature mechanical properties at a temperature of 250°C.

The results are shown in Table 1.

As is clear from Table 1, the aluminum alloy of the present invention, which has excellent thermal neutron absorption ability and high-temperature strength,
It can be seen that both thermal neutron absorption ability and high-temperature mechanical properties are superior to comparative alloys.

Example 2 Regarding alloys No., 2, No. 6 shown in Table 1 of Example 1, aluminum alloy ingots (50 mm thick) with different crystal grain sizes were heated at 350 to 600°C. After soaking at high temperature, the plate thickness is 5m by hot rolling.
A plate material of m was manufactured, and then this plate material was annealed at 350° C. for 2 hours to obtain a test material.

Thermal neutron absorption capacity and 250°C of these test materials
The mechanical properties at high temperatures were investigated and the results are shown in Table 2.

It is clear from Table 2 that the crystal grains of the aluminum alloy ingot and the temperature of the soaking treatment are outside the range of conditions specified in the method for producing an aluminum alloy with excellent thermal neutron absorption ability and high-temperature strength according to the present invention. It can be seen that although the thermal neutron absorption capacity is roughly the same, the mechanical properties are significantly inferior.

1. Effects of the Invention) As explained below-1, the method for producing an aluminum alloy having excellent thermal neutron absorption ability and high temperature strength according to the present invention has the above-mentioned structure or has excellent thermal neutron absorption ability. Moreover, it has the effect of being excellent in strength at high temperatures.

Claims (1)

[Claims] Contains 0.2 to 30 wt% of Gd, 0.5 to 6 wt% of Mg, and further contains 1 wt% or less of Mn, 0.3 wt% or less of Cr, and 0.3 wt% of Zr.
Contains one or more types selected from the following: wt%, V0.3wt% or less, B3wt% or less, Li3wt% or less, Si1wt% or less, Zn1wt% or less, Cu1wt% or less, Ni2wt% or less, Ti1wt% or less. , the grain size of the aluminum alloy ingot consisting of the remainder Al and unavoidable impurities is set to 5 mm or less,
A method for producing an aluminum alloy having excellent thermal neutron absorption ability and high-temperature strength, the method comprising performing soaking treatment at a temperature of 400 to 550°C for 2 hours or more.