JPH01255A - High hardness non-magnetic stainless steel for electronic equipment parts - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-hardness non-magnetic stainless steel suitable for use in electronic equipment parts that utilize magnetism, and particularly suitable for various shaft circumferences of VTRs or VTR cassette tapes.

[Conventional technology]

Components used in electronic devices that use magnetism must be non-magnetic, especially for video and audio storage devices (hereinafter referred to as VT).
Various types of shafts such as cylinder shafts used in VTR cassette tapes, capstein shafts, and guide rollers and guide pins used in VTR cassette tapes are required to have high hardness in terms of wear resistance. Such parts are also required to have excellent corrosion resistance, and from this point of view, austenitic stainless steel is often used as the material. - For boat fishing, stainless steel such as 5tlS305.5tlS316, which has austenite 141 which is stable at room temperature, has been widely used.

Guide rollers used in VTR cassette tapes are required to have high hardness because they wear out and cause scratches on the tape when used for a long time, and Vickers hardness is 4.
00 or more is required. However, the above-mentioned austenitic stainless steel has a Vickers hardness of 4.
In order to obtain a value of 00 or more, cold working is required, and cold working makes it impossible to ensure nonmagnetism due to the formation of work-induced martensite.

Austenitic stainless steels are known in which a part of Ni is replaced with Mn and the C and N contents are increased to increase hardness (Japanese Unexamined Patent Publication No. 84324/1983, Japanese Unexamined Patent Publication No. 61/1983)
No. 213351, etc.) had poor hot workability, and improvements were strongly desired from the viewpoint of manufacturability.

In addition, conventionally, as a manufacturing method of non-magnetic steel, JP-A-61-
Although the method described in Japanese Patent No. 37953 is known, high hardness and hot workability are not considered.

[Problem that the invention seeks to solve]

In order to improve this conventional problem, the present invention aims to improve Mn-
Focusing on Ni-Cr austenitic stainless steel, we have developed a stainless steel for electronic device parts that has excellent hot workability and corrosion resistance, and has a Vickers hardness of 400 or more and a magnetic permeability of 1.01 or less after cold working. The object of the present invention is to provide stainless steel suitable for various types of shafts used in VTRs or VTR cassette tapes.

[Means and effects for solving the problem] For this purpose, the present inventor studied various compositions of Mn-Ni-Cr austenitic stainless steel, and achieved this goal.

The gist of the present invention is that in weight %, C; 0.1 to 0.3%;
Si: 0.1-2%, Mn: 8-15%, S≦0.
006%, Ni; 3-8%, Cr; 18-22%,
O≦0.01%, N; 0.1-0.5%, Ca;
0.0001 to 0.02%, the balance being Fe and unavoidable impurities, and Nieq of formula (1) is 18 or more, (
2) An electron having a composition in which Cr@q in the formula is 23 or less, pv in the formula (3) is 0 or less, and has a Vickers hardness of 400 or more and a magnetic permeability of 1.01 or less after cold working. High hardness non-magnetic stainless steel for equipment parts.

Ni@q=Ni%+30C%+25N%+〇, 5Mn%
−・−・・・・・・(1) Creq Tomi Cr%+1.5Si
%・・・・・・・・・・・・・・・・・・・・・
...(21PV-5(pp+m) + O(ppm)
-0,8Ca (pps) -30...- (3) The target material of the present invention is a material that has been hot-worked and then cold-worked, and its shape is plate (strip and sheet), wire, and tube. The plate can be drawn into a tubular shape, or it can be further cold-worked such as drawing, and the wires and tubes can be left as they are, or they can be further cold-worked such as drawing, to form VTR cylinder shafts and Capstein shafts. , used for various shafts such as guide rollers and guide pins of VTR cassette tapes.

The reasons for limiting the constituent elements of the present invention will be explained below.

C is an element that stabilizes austenite and at the same time contributes to increasing hardness. These effects are not sufficient for electronic device parts at less than 0.1%, and at 0.3%,
%, carbides will precipitate at the austenite grain boundaries, thereby deteriorating the corrosion resistance for electronic device parts. Therefore, C was set at 0.1 to 0.3%.

Si is an element that improves work hardenability, but 0, 1
If it is less than 2%, it is not sufficient, and since it is a ferrite stabilizing element, if it exceeds 2%, it becomes two phases of ferrite and austenite, increasing the magnetic permeability.

Therefore, si was set to 0.1 to 2%.

Mn has the effect of stabilizing the austenite structure at a low cost, and is an element necessary to ensure the nonmagnetism of steel. This effect is not sufficient for use in electronic device parts if it is less than 8%, and if it exceeds 15%, the effect is saturated. Therefore, Mn was set to 8 to 15%.

When S exceeds 0.006%, there is a possibility that hot workability may be inhibited. Therefore, S was set to 0.006% or less.

Ni is a potent austenite stabilizing element, with 3%
If it is less than 8%, it will not be possible to ensure non-magnetism for electronic device parts, and if it exceeds 8%, it will not only be excessive in terms of stabilization, but will also increase costs, which is undesirable.
Therefore, Ni was set at 3 to 8%.

Cr is 18% from the viewpoint of corrosion resistance for electronic equipment parts.
If it is less than 22%, it is insufficient, and if it exceeds 22%, two phases of ferrite and austenite are formed, increasing the magnetic permeability. Therefore, the Cr content was set at 18 to 22%.

If 0 exceeds 0.01%, hot workability may be inhibited. Therefore, 0 was set to 0.01% or less.

Like C, N is an austenite stabilizing element and at the same time an element that contributes to solid solution hardening. This effect is insufficient for electronic device parts at less than 0.1%, and
If it exceeds 5%, it is not preferable because it may cause defects such as blowholes in the steel ingot. Therefore, N is 0.
The content was set at 1% to 0.5%.

Ca is an element that improves hot workability, and its effect is insufficient at less than 0.0001%, and at 0.02%
Even if the amount is added in excess of the above amount, the effect will be saturated, which is not preferable in terms of cost. Therefore, Ca is 0.0001-0.02%
And so.

Nieq is an index indicating austenite stability, and is 1
If it is less than 8, the magnetic permeability after annealing or cold working is 1.0.
Since it exceeds 1, non-magnetism cannot be ensured. Therefore, Nie
q was set to 18 or more.

Creq is an index indicating ferrite stability, and when it exceeds 23, it becomes a two-phase ferrite-austenite i3
Increase magnetic flux. Therefore, Craq was set to 23 or less.

pv is an index showing hot workability, and if it exceeds O, problems such as cracking of the material during hot working will occur.

Therefore, pv was set to be less than or equal to θ.

When Nieq and Craq are within the above ranges, hot workability is improved and manufacturability is significantly improved.

The hardness was set to a Vickers hardness of 400 or more, since guide rollers used in VTR cassette tapes would wear out and cause scratches on the tape when used for a long time if the Vickers hardness was less than 400.

If parts with a magnetic permeability exceeding 1.01 are used in equipment that uses magnetism, there is a risk of disturbing the magnetic field, so the magnetic permeability should be set to 1.01.
．． 01 or less.

〔Example〕

Austenitic stainless steels as shown in Table 1 were hot-worked and further cold-worked into plates, wires, and tubes. It was temporarily drawn into a tube. The hot workability, hardness, magnetic permeability, and corrosion resistance of these materials are shown in Table 2. For hot workability, those that cracked during hot working were designated as X, and those that did not crack were designated as O.

The hardness is the Vickers hardness measured according to JIS Z2244 for a material cold-worked at a working rate of 50% after final annealing, and the magnetic permeability is a value for a material cold-worked at a working rate of 50% after final annealing. Corrosion resistance is JISZ2371
Measured according to the salt spray test, and those with rust are marked as ×.
Items that did not rust are indicated by O.

It can be seen that all of the steels of the present invention have excellent hot workability and corrosion resistance, and at the same time, have significantly higher hardness and lower magnetic permeability than the comparative steels.

! [Effects of the Invention] As is clear from the above, according to the present invention, a highly hard and non-magnetic stainless steel with excellent hot workability and corrosion resistance can be obtained, and it can be used as a component for electronic devices that utilize magnetism. , especially V
Used on each bridge shaft of a TR or VTR cassette tape, it exhibits corrosion and abrasion resistance without disturbing the magnetic properties of the device.

Claims (1)

[Claims] In weight%, C: 0.1 to 0.3%, Si: 0.1 to 2
%, Mn; 8~15%, S≦0.006%, Ni; 3~
8%, Cr; 18-22%, O≦0.01%, N; 0.
1 to 0.5%, Ca; 0.0001 to 0.02%, balance consisting of Fe and unavoidable impurities, and Nieq expressed by the following formula is 18 or more, Creq is 23 or less, PV
A high-hardness non-magnetic stainless steel for electronic device parts, which has a Vickers hardness of 400 or more and a magnetic permeability of 1.01 or less after cold working. Nieq=Ni%+30C%+25N%+0.5Mn%
・・・・・・・・・(1) Creq=Cr%+1.5S
i%・・・・・・・・・・・・・・・・・・(2)P
V=S(ppm)+O(ppm)−0.8Ca(ppm
)-30...(3)