JPH0466651A - Non-magnetic material for coin excellent in coining property and wear resistance - Google Patents

Abstract

PURPOSE:To offer a soft material excellent in coining properties and corrosion resistance and showing non-magnetic properties even after working by specifying the content of C, Si, Mn, Ni, Cr or the like in an alloy. CONSTITUTION:The compsn. of a non-magnetic material for coins is formed of, by weight, <=0.03% C, <=0.50% Si, <=3.00% Mn, 8 to 16% Ni, 16.00 to 20.00% Cr, <=0.03% N, <=5.00% Cu and the balance Fe with inevitable impurities. Furthermore, the content of each components is regulated so that K value expressed by an expression I and U value expressed by an expression II will simultaneously be satisfied. If required, this material is incorporated with one or more kinds among <=0.5% Ti, <=0.5% Nb, <=0.5% V, <=0.5% Zr, <=3.0% Mo, <=1.5% Al and <=0.03% B. This non-magnetic material for coins has good scuffing resistance and wear resistance after coining by suitable work hardening.

Description

[Detailed description of the invention] [Industrial application field] The present invention is soft and has excellent coining and coining properties.

The present invention relates to a non-magnetic coin material that has good scratch resistance and abrasion resistance due to moderate work hardening after coining processing, and has excellent corrosion resistance.

[Conventional technology]

What are the characteristics required for coin materials?

■It must be soft in terms of coining properties (material hardness H
v is 130 or less).

■It is hard to get scratched after cocoining.

■It has excellent wear resistance.

■It must be non-magnetic (magnetic permeability (μ
- 1) is 0.1 or less), and in addition, ■ relatively low or appropriate price is required in terms of cost, and ■ solid appearance,
In some cases, texture and design characteristics are required. Naturally, it is also required to have excellent corrosion resistance.

Currently, the coin materials commonly used for coins include pure nickel, cupronickel (Cu-25N i), and nickel silver (Cu-20
There are Cu and Ni systems such as N + -15Z n). In addition, coins for games that have recently been increasing in use include coins made of ordinary steel, brass, or pure copper plated with Ni to prevent staining, and coins made of ferritic stainless steel coated with color. In part (Cu-36Z n
-9N i) There are also examples where the material is used as is, such as in the case of the i) series.

[Problem that the invention seeks to solve]

Among the coin materials mentioned above, pure nickel and cupronickel (Cu-
25Ni), nickel silver (Cu-20N 1-15 Z n)
, etc., and (Cu-36Z n
-9N +) alloy is expensive, and has low work hardening and is soft, so it has problems such as being easily scratched after coining.

In addition, ordinary steel, brass, and pure copper are coated with Ni plating to prevent stains, which causes problems in productivity and increased costs.Furthermore, they have low work hardening and are soft, so they are easily scratched after coining. are doing.

In addition, coins made of colored 9-ferrite stainless steel and coins made of ordinary steel have an inherent drawback that they cannot be used in devices that use electronic mechanisms because they are magnetic.

For these reasons, austenitic stainless steel (9), which is relatively inexpensive, can be used as a raw material, becomes hard after coining, and is nonmagnetic in cold-rolled and annealed sheets, has begun to attract attention. In metastable steels such as Shigashi S[1S304, the hardness after coining is sufficiently satisfactory due to work hardening, but there are problems such as the production of a large amount of work-induced martensite that becomes magnetic. There was a point.

[Means for solving problems]

The present invention solves one of the drawbacks of the conventional coin materials mentioned above.
In order to provide a material for non-magnetic coins that solves all of these problems, the present inventors have developed austenite, which is the softest and has the lowest work hardening that can be produced using current industrial technology, and has excellent performance as a material for non-magnetic coins. We have discovered a new type of stainless steel.

That is, according to the present invention, 1% by weight C: 0.03% or less.

St: 0050% or less.

Mn: 3.00% or less.

Ni: 8% or more to 16% or less.

Cr: 16.00% or more to 20.00% or less.

N: 0.03% or less.

Cu: 5.00% or less.

and, in some cases, further.

Ti: 0.5% or less Nb 10.5% or less.

V: 0.5% or less.

Zr; 0.5% or less.

Mo: 3.0% or less.

Al: 1.5% or less.

B, 0.03% or less.

of the above-mentioned components such that the remainder consists of Fe and unavoidable impurities, and the U value and U value expressed by the following formulas (1) and (2) are simultaneously satisfied. To provide a non-magnetic material for coins having excellent coining properties and wear resistance by adjusting the content.

K=20.5+13.0×C+0.99XSt 1.
lXMn-Ni+o,,ax Cr-0,4X Cu+
117. IX N≦19, 5-(1)U =42.
3+79.8X C+0.34X S i 1.29
x Ni+0.90X Cr Cu+68.8X N
≦45 -- (2) [Function] In the steel having the above-mentioned components, in the range where it has a chemical composition that satisfies the 0 formula and the 0 formula at the same time, it has a low hardness ( Hv of 130 or less), and remains non-magnetic (magnetic permeability μm1 of less than 0.1) even after coining.

The effect of each component in the steel material for coins of the present invention and the reason for limiting the content will be explained individually as follows.

C: The content of 1 C in the steel that is the material of the present invention is
The lower it is, the softer the material can be.

The range that can be stably achieved with current technology and allow for an increase in hardness due to solid solution strengthening is C, 0.03% or less.

St;Si is preferably lower from the point of view of softness,
In the production of steel, deoxidation becomes insufficient, so it has to be added to a certain extent, but if it exceeds 0.50%, the effect is saturated, so the upper limit is set at 0.50%.

Mn: The more Mn it contains, the softer it becomes.
Even if added in excess of 3.00%, the effect will be saturated, so the upper limit is set at 3.00%.

Ni: Ni is an essential element for austenitic stainless steel, and should be contained in an amount of 8% or more in consideration of the stability of its austenite phase.

In addition, considering economic efficiency, it is desirable that the ratio be 16% or less.

Cr: 16% or more of Cr is required to maintain sufficient corrosion resistance as a stainless steel for coins, but if it is contained in too large an amount, it will increase hardness and deteriorate workability.
0% or less.

NUN is an austenite-forming element, but if it is contained in an amount exceeding 0.03%, it will cause an increase in hardness due to solid solution strengthening and deterioration of surface properties, so it should be kept at 0.03% or less.

Cu: Cu is an austenite-forming element and is an extremely effective element for reducing hardness and work hardening.
If added in excess of 5%, hot workability deteriorates and manufacturability decreases, such as edge breakage during hot rolling.
% or less is desirable.

Ti, Nb, V, and Zr serve to refine the metal structure and prevent roughening of the surface after forming. However, even if more than 0.5% of each is added, the effect is saturated, so the amount is set to 0.5% or less.

Although AI is highly effective as a deoxidizer, adding 1.5% or more increases the strength, so the content is set at 1.5% or less.

Mo is an element effective in improving corrosion resistance, but even if it is added in an amount exceeding 3%, the effect will be saturated, so it is limited to 3.0% or less. .

B effectively contributes to the prevention of hot cracking, but if it exceeds 0.03%, intergranular corrosion resistance decreases, so it should be kept at 0.03% or less.

In addition to the above individual component regulations, in order to have low hardness and remain non-magnetic even after coining, the value must be 19.5 or less according to the above-mentioned formula (1), and the U value according to formula (2) must be 45. It is important to limit each component as follows. This point is illustrated by the test results below.

13 steel types (NCLI~Cu+
117, and these steel pieces were hot rolled at an extraction temperature of 1220°C to obtain a hot rolled steel strip of 3.81. This hot-rolled steel strip was subjected to 1100" C1 soaking 1 winO hot-rolled plate annealing and pickling, and then 1.52mm thick (cold rolling rate 60
%), and the magnetic permeability (μm1) was investigated. Also.

This cold-rolled material was annealed at 1050° C. for 1 sin of soaking and pickled, and the hardness was measured. Figure 1 shows the relationship between the value of each sample and the hardness after cold rolling and annealing. It can be seen that the hardness increases as the value of hardness increases. In order to prevent the hardness from exceeding 130, it is necessary to set the value to 19.5 or less. Figure 2 shows the U value of each sample material and the magnetic permeability (μ
It can be seen that the magnetic permeability (μm1), which shows the relationship of m1), increases as the U value increases. Magnetic permeability (μm1) is 0.
In order not to exceed 1, it is necessary to make the U value 45 or less.

[Example] Table 2 shows the chemical compositions of the steels of the present invention (21 to N+130) and comparative steels (14 to 20), and the fineness calculated from formulas (1) and (2) above. An austenitic stainless steel having these components, whose value and U value are shown together, was melted and hot rolled at an extraction temperature of 1220°C to obtain a hot rolled steel strip of 3.81. 1100 to this hot rolled steel strip
℃, hot-rolled sheet annealing and pickling at soaking temperature of 1 inch, then 1
．． It was cold rolled to a thickness of 52 mm (cold rolling ratio 60%) and its magnetic permeability (μm1) was investigated. In addition, this cold-rolled material has a temperature of 1050°C.
1 soaking, 1 win annealing and pickling.

Hardness measurements were carried out. The results are also listed in Table 2.

From Table 2, although the hardness of comparative steel 14.15.17.19.20 is lower than 130, the U value is higher than the specified value (45), so the magnetic permeability (μm1) is 0.1 or more, and the magnetic property is There is. Comparative steels 16 and 18 also have hardness and magnetic permeability (
μm1) is high. On the other hand, the hardness of tunings 21 to 30 of the present invention that satisfy equations (1) and (2) is 13.
0 and the magnetic permeability (μm1) is lower than 0.1, which means that it is extremely softer than conventional austenitic stainless steel and remains non-magnetic even after processing. For example, it has properties that cannot be obtained with conventional austenitic stainless steel.

In other words, ■It is extremely soft with low hardness and little processing softening, and ■Magnetic permeability (μm1) is 0 even after 60% cold rolling.
．． Stainless steel has an advantageous property as a coin material, that is, it maintains non-magnetism of 1% or less. As a result, the material of the present invention can be used in fields such as austenitic stainless steels such as 5US304, which cannot be used due to their high work hardening and magnetic properties after processing. It can be suitably used for coins in various fields.

[Brief explanation of drawings]

Figure 1 shows the relationship between the hardness and hardness of cold rolled steel strip in the annealed state, and Figure 2 shows the magnetic permeability (μm1) after 60% cold rolling.
) and the U value.

Claims (1)

[Claims] (1) In weight%, C: 0.03% or less, Si: 0.50% or less, Mn: 3.00% or less, Ni: 8% or more and 16% or less, Cr: 16.00% or more and 20 .00% or less, N; 0.
03% or less, Cu; 5.00% or less, the remainder consists of Fe and unavoidable impurities,
A non-magnetic material for coins having excellent coining properties and wear resistance, which is obtained by adjusting the content of the above components so as to simultaneously satisfy the K value and U value expressed by the following formulas (1) and (2). . K=20.5+13.0×C+0.99×Si−1.1
×Mn-Ni+0.4×Cr-0.4×Cu+117.
1×N≦19.5 (1) U=42.3+79
．． 8×C+0.34×Si−1.29×Ni+0.90
×Cr-Cu+68.8×N≦45 (2
)(2) In weight%, C: 0.03% or less, Si: 0.50% or less, Mn: 3.00% or less, Ni: 8% or more to 16% or less, Cr: 16.00% or more 20.00% or less, N; 0.
03% or less, Cu; 5.00% or less, furthermore, Ti; 0.5% or less, Nb; 0.5% or less, V; 0.5% or less, Zr; 0.5% or less, Contains one or more of Mo: 3.0% or less, A1: 1.5% or less, B: 0.03% or less, and the remainder consists of Fe and inevitable impurities, and the following (1) Equation and (2)
A non-magnetic material for coins having excellent coining properties and wear resistance, which is obtained by adjusting the content of the above-mentioned components so as to simultaneously satisfy the K value and U value expressed by the formula. K=20.5+13.0×C+0.99×Si−1.1
×Mn-Ni+0.4×Cr-0.4×Cu+117.
1×N≦19.5 (1) U=42.3+79
．． 8×C+0.34×Si−1.29×Ni+0.90
×Cr-Cu+68.8×N≦45・・・・・・・・・(
2)