JPH0774418B2 - Rust-resistant soft magnetic steel plate with high hardness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rust-resistant soft magnetic steel sheet having high hardness, in particular, having a micro Vickers hardness (1 kgf) of 180 or more, and its longitudinal grain Br and Hc. The present invention relates to a soft magnetic steel sheet having a hysteresis characteristic of 0.50 T · A / cm or less and having rust resistance equivalent to that of stainless steel.

(Prior Art) Magnetic steel sheets are used in a very wide range of fields as soft magnetic materials, but due to the recent diversification of electrical equipment and performance improvements, many are used under severe conditions. In response to this, the characteristics required for electromagnetic steel sheets are becoming diverse. For example, as a core material for a magnet switch, a steel plate having hardness and magnetic characteristics equal to or higher than that of a conventional electromagnetic steel plate and excellent in rust resistance is required.

As a technique for dealing with this, a method for producing a soft magnetic material, which is based on silicon steel and has rust resistance by adding chrome to it, has been used as a method for producing a soft magnetic material.
The method described in Japanese Patent Publication No. 4 or Japanese Patent Publication No. 56-29952 is proposed.

In the former case, C ≦ 0.4%, S ≦ 0.2%, Cr11.5 to 20%, Si
1-6% and Ti 0.5-5% are stipulated. In the latter, C
≤0.05%, N≤0.05%, Cr3 ~ 11%, Si + Al≤2%, Ti is 5
It is specified that (C + N)% or more and 1% or less.

In the present invention, Japanese Patent Application No. 60-
113153 technical idea, that is, high-purity steel, specifically C
Based on the idea of achieving excellent magnetic properties by setting ≦ 0.01%, N ≦ 0.01%, and S ≦ 0.005%, the effect of Ti described above is effectively utilized to increase the margin of high purity steel. It is an enlarged version.

(Problems to be Solved by the Invention) In the prior invention (Japanese Patent Application No. 60-113153), C0.0
It is a necessary condition in terms of steel composition that the content is 1% or less and N0.01% or less.
It is not industrially impossible to obtain stable steel with i, 5.5 to 11.5% Cr, but it involves a considerable cost increase, and magnetic aging occurs when Cr is 6% or less. Considering two points as problems to be solved, studies were conducted to more easily obtain a soft magnetic steel sheet having desired properties.

(Means for Solving Problems) As a result of various studies, the present inventors have found that by adding Ti in an amount commensurate with the C and N contents, that is, (C +
By newly controlling N)% ≦ Ti% ≦ 4 (C + N)%, it is newly found that it is possible to easily obtain a high hardness rust resistant soft magnetic steel sheet with excellent magnetic properties without magnetic aging. It came out.

The present invention will be described in detail below.

First, the steel composition will be described. Cr is added to improve rust resistance, but the magnetic flux density decreases with addition, so the upper limit is 13
%, While the lower limit is 5% from the viewpoint of the effect of improving rust resistance.

Si is contained in an amount of 2.0% or more in order to increase the specific resistance of steel, reduce eddy current loss, reduce iron loss, and increase hardness. When used for a magnet switch, the hardness is desired to be high from the viewpoint of wear resistance of the end face of the core, and a micro Vickers hardness Hv (1 kgf) of 180 or more is recently required. As one necessary condition for satisfying this, Si is set to 2.0% or more. On the other hand, as the content increases, the magnetic flux density decreases and the cold rolling property deteriorates, so the upper limit of addition is made 3.5%.

Al has the effect of increasing the specific resistance of steel and lowering the iron loss like the former Si, but from the economical aspect, it is made 1.5% or less.

P can be added as an element that increases hardness,
0.1% or less, because the slab becomes easily cracked.

It is already well known that N, S, and C form nitrides, sulfides, carbides, and composite compounds thereof and deteriorate magnetic properties, so that the lower the content, the better.

However, stable reduction of both N and C to 0.01% or less with the current steelmaking technology involves a considerable cost increase. Therefore, Ti is added to make N and C harmless. I considered that.

Specific examples will be described below.

(Example 1) Steels having the components shown in Table 1 were melted by vacuum melting, ingot-cast and hot-rolled by a usual method, and finished to 2.0 mmt. The hot-rolled sheet was heat-treated at 950 ° C for 2 minutes, then pickled and cold-rolled to 0.50 mmt. 950-1000 ℃ × 30 on this cold rolled sheet
Second annealing was performed and magnetic properties were measured. Measurement of magnetic properties and confirmation of aging are 60 mm long in the rolling (L) direction.
A 300 mm veneer was used, and the results are shown in Table 2. It is clear from this that aging can be suppressed by adding Ti. However, this effect is not sufficient when the Ti addition amount <(C + N)% as in the case of Steel A.
Table 3 shows the change in iron loss when SRA (750 ° C x 2h) after annealing. When Ti> 4 (C + N)% as in the case of Steel D, the iron loss deteriorates due to SRA. It turned out to be big.

From the above, C <0.02%, N <0.02%, S <0.01
It has been newly found that, in a high-purity steel with a level of%, (C + N)% ≦ Ti ≦ 4 (C + N)% should be set as an appropriate addition range of Ti.

(Example 2) Steels having the components shown in Table 4 were melted by vacuum melting, ingot-cast and hot-rolled by a usual method, and finished to 2.0 mmt. The hot-rolled sheet was heat-treated at 950 ° C for 2 minutes, then pickled and cold-rolled to 0.50 mmt. The cold-rolled sheet was annealed at 1000 ° C for 30 seconds, and the magnetic characteristics and hardness were measured. The results are shown in Table 5 and FIG. 1, and clearly from Table 5, although the magnetic flux density, iron loss, and Br × Hc are slightly deteriorated by the addition of Ti,
As described above, the amount of Ti added is (C + N)% ≦ Ti% ≦ 4 (C + N
By controlling the N)% range, aging can be suppressed, and deterioration of magnetism due to SRA can be minimized. The hardness is as shown in Fig. 1.
It was confirmed that the Ti-added material was about 20 points harder than the Ti-free material. The hardening mechanism is thought to be due to the refinement of crystal grains and the precipitation hardening of TiC, TiN, etc., but the important point is that the deterioration of the magnetic properties due to such hardening can be almost ignored. It is small.

(Effects of the Invention) The present invention makes it possible to produce a rust-resistant soft magnetic steel sheet with high hardness at low cost without significantly impairing the magnetic properties of conventional non-oriented electrical steel sheets, and to produce magnet switches and the like. In addition to the need for the rust-prevention treatment which has been conventionally required, it has great effects such as extending the life of these products and improving their reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a chart showing the difference between the Si content of soft magnetic steel and the micro Vickers hardness depending on the presence or absence of Ti addition.

Claims (3)

[Claims] 1. C0.02% or less by weight%, Si2.0 to 3.5%, Cr5.0
~ 13%, N0.02% or less, Al1.5% or less, P0.1% or less, S0.01%
Including the following, the Ti content is (C + N)% ≦ Ti% ≦ 4 (C +
N)%, the balance being Fe and unavoidable impurities, and a rust resistant soft magnetic steel sheet with high hardness. 2. The hardness is Micro Vickers hardness Hv (1 kgf)
The rust-resistant soft magnetic steel sheet having high hardness according to claim 1, which is 180 or more. 3. The rust-resistant soft magnetic steel sheet with high hardness according to claim 1, which has a hysteresis characteristic of a product of Br and Hc of 0.50 T · A / cm or less.