JPH08193251A - Powdery material of nonmagnetic stainless steel - Google Patents

Abstract

PURPOSE: To obtain a fine powdery material of a nonmagnetic economical austenitic stainless steel having satisfactory corrosion resistance. CONSTITUTION: An austenitic stainless steel consist.ing of, by weight, 0.17-0.4% C, 8-13% Ni, 16-26% Cr, <=0.10% P and <=0.10% S as alloying elements and the balance Fe with an element added for deoxidation and inevitable impurities is water- or gas-atomized to obtain the object fine powder having <=100μm, preferably <=50μm particle diameter. The stainless steel may further contain 1-6wt.% Mo. The steel is nonmagnetic as atomized, has satisfactory corrosion resistance and is economical.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic aggregate such as a composite material formed by mixing fine metal powder and a synthetic resin material, and a low melting metal sintered composite material.

[0002]

2. Description of the Related Art Fine powder of austenitic stainless steel, which is non-magnetic and has excellent corrosion resistance, has been attracting attention as an aggregate of a composite material obtained by mixing and molding fine metal powder such as conductive resin material and resin material for electromagnetic shielding and synthetic resin. ing. Further, it is considered that the fine powder of austenitic stainless steel is also useful as a non-magnetic aggregate such as a low melting point metal sintered composite material.

[0003] Conventionally, SUS is often used for applications where magnetism is disliked.
Although 304, SUS316, and other austenitic stainless steel materials are used, these steels are usually magnetized when rapidly cooled from high temperature to form a large amount of δ-ferrite, or when subjected to strong plastic working. 1000 ~
It is difficult to be magnetized by aligning the metal structure by solution treatment by heating at 1150 ° C and removing processing strain (non-magnetic)
It is used as a state.

The fine powder of SUS304 or SUS316 equivalent steel is pulverized directly from the molten metal by any of the water atomizing method, the gas atomizing method, the centrifugal atomizing method and the like, so that magnetism is inevitable in the powder state. When these fine powders are used as a sintered body, they can be made non-magnetic by performing solution treatment after sintering. However, if the solution treatment is performed in the state of the fine powder, the fine powder has a problem of sintering, and it has been impossible to obtain the non-magnetic stainless steel powder by an economical method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made against the background of the above circumstances, and its purpose is to:
An object of the present invention is to provide an economical austenitic stainless steel fine powder material that is non-magnetic and has good corrosion resistance.

[0006]

In order to solve the above-mentioned problems, the non-magnetic stainless steel powder material of the present invention has (1) an alloy element content ratio of C: 0.17 to 0.4 w.
t%, Ni: 8 to 13 wt%, Cr: 16 to 26 wt
%, P: 0.10 wt% or less, S: 0.10 wt%
The following is characterized in that the balance consists of Fe, an element added for deoxidation and inevitable impurities, and has a particle size of 100 μm or less. (2) It is characterized in that Mo: 1 to 6 wt% is contained in addition to the alloy elements. (3) In (1) or (2), the particle size is 50 μm or less.

Next, the reasons for limiting the components of the non-magnetic stainless steel powder material in the present invention will be explained. C: 0.17 to 0.4 wt% C is an element that suppresses the formation of δ-ferrite during solidification of steel, and is an element that stabilizes austenite by lowering the martensite transformation point, It plays an important role in demagnetizing the stainless steel powder material of the present invention. In order to exert these effects, it is necessary to contain 0.17 wt% or more of C.
However, if it is contained excessively, it combines with Cr and Mo to form a large amount of carbides, lowers the concentration of Cr and Mo in the base iron, and impairs the corrosion resistance of steel, so the upper limit of the C content is 0. .4
wt%.

Ni: 8 to 13 wt% Ni is an element that stabilizes austenite of steel and increases corrosion resistance, and in order to exert these effects, it is 8
It is necessary to contain wt% or more of Ni. However, even if it is contained excessively, the effect is saturated and only the cost of steel is increased, so the upper limit of the Ni content is set to 13 wt%.

Cr: 16 to 26 wt% Cr is an element that imparts corrosion resistance to steel, and its content is 16
If it is less than wt%, the corrosion resistance is insufficient. However, when the Cr content exceeds 26 wt%, this effect saturates.
The upper limit is 26 wt%. P: 0.10 wt% or less P increases its strength when an appropriate amount is added to austenitic steel, but if added in excess, it forms a hard brittle nitride and impairs the mechanical properties of the steel. Is limited to 0.10 wt% or less.

S: 0.10 wt% or less S forms a compound with Fe to make the steel brittle, and combines with Mn to form a non-metallic inclusion having a high melting point and impair the cleanliness of the steel. Further, since a compound is formed with Mo to reduce the amount of solid solution Mo in the steel, the S content is limited to 0.1 wt% or less. Mo: 1 to 6 wt% Mo is an element that increases the corrosion resistance of steel, particularly the corrosion resistance to sulfate ions, and a content ratio of at least 1 wt% or more is necessary to exhibit its effect. However, even if added too much, the effect will be saturated and it will only increase the cost of steel, so
The upper limit of Mo content is 6 wt%.

In addition, 0.3 wt% as a deoxidizing element of steel
The following Mn, 1.5 wt% or less Si and 0.05 w
You may contain t% or less of Al. The non-magnetic stainless steel powder material of the present invention is instantly atomized from molten steel by a water atomization method or a gas atomization method and rapidly cooled to form a fine powder. At this time, if the particle size formed by spraying is too large, the cooling at the time of powder molding becomes slow, and demagnetization becomes insufficient. Therefore, in the non-magnetic stainless steel powder material of the present invention, the particle size of the powder is 100 μm or less,
The thickness is preferably 50 μm or less.

[0012]

EXAMPLES Examples of the present invention will be specifically described below.
Alloy powders having the chemical compositions shown in Table 1 were produced by a water atomization method or a gas atomization method. Table 2 shows various properties of these alloy powders.

[0013]

[Table 1]

[0014]

[Table 2]

The magnetism was tested as follows. If an appropriate amount of alloy powder is placed on paper, a magnet with a magnetic flux density of 12 kG is applied under the paper, and the magnet is moved along the paper surface, if the alloy powder on the paper moves with the movement of the moving magnet, The alloy powder shall be magnetized, and shall not be magnetized unless it moves. None of the examples of the invention magnetized. C,
Comparative Example 1 having a low Ni and Cr content was magnetized. Also,
The alloy composition was the same as that of Example 1, but Comparative Example 3 having a large powder particle size was magnetized.

The corrosion resistance test was conducted as follows. After 2 g of the alloy powder sample was degreased and washed, it was put into 100 ml of pure water at 80 ° C. and held for 170 hours to quantitatively analyze the amount of eluted iron (ICP emission spectroscopy). In Table 2, the corrosion resistance was determined by setting the Fe elution amount of SUS316L to 1, ∘ when the Fe elution amount of the sample was 1 or less, ◯ when it was more than 1 and less than 10, and Δ when 10 or more and less than 15 1
The case where it exceeded 5 was marked with x. From Table 2, it is understood that the corrosion resistance is inferior in Comparative Examples 1 and 2 in which the alloy composition is out of the range of the present invention.

[0017]

As described above, according to the present invention, a non-magnetic stainless steel powder material which is non-magnetic, has good corrosion resistance, and is economical can be obtained. INDUSTRIAL APPLICABILITY The present invention is an aggregate of a composite material obtained by mixing and molding a fine metal powder and a synthetic resin such as a conductive resin material or a resin material for electromagnetic shielding, and a non-magnetic aggregate such as a low melting point metal sintered composite material. It can be said to provide a useful material.

Claims (3)

[Claims] 1. The content of alloying elements is C: 0.17 to 0.4 wt%, Ni: 8 to 13 wt%, Cr: 16 to 26 wt%, P: 0.10 wt% or less, S: 0.10 wt%. % Or less, the balance consisting of Fe, elements added for deoxidation and inevitable impurities,
A non-magnetic stainless steel powder material having a particle size of 100 μm or less. 2. In addition to the alloy elements, Mo: 1-6w
The non-magnetic stainless steel powder material according to claim 1, characterized in that it contains t%. 3. The non-magnetic stainless steel powder material according to claim 1 or 2, wherein the particle size is 50 μm or less.