JPH05331602A - Non-oriented electrical steel sheet with excellent machinability - Google Patents

Abstract

(57) [Summary] [Purpose] Various characteristics other than machinability required for electrical steel sheets,
That is, machinability is improved without impairing magnetic properties, punchability, weldability, and the like. [Constitution] C: 0.007% or less, Si: 0.5% or less, Al: 0.
1% or less and P: 0.1% or less, and Mn is 0.3
%, And the ratio to the amount of S in which the amount of inclusion is suppressed to 0.01% or less satisfies the following formula 20 ≦ Mn / S ≦ 80.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet suitable for use as an iron core material of a motor for household electric appliances and a small motor, and is particularly intended to improve its machinability. ..

[0002]

2. Description of the Related Art Generally, a low Si electrical steel sheet having a Si content of about 0.5 wt% (hereinafter simply referred to as%) or less has a low iron content due to a low Si content, but has a high magnetic permeability. Have,
In addition, because of its low price, its demand is extremely large, centering on motors for household appliances and small motors. Since such a motor is mass-produced and used, it is indispensable to supply it at a low cost. Therefore, in the cutting process, which is a part of the motor production process, it is particularly important to inexpensively manufacture a steel material that can prolong the life of the cutting tool, that is, supply a steel material having good machinability.

As a non-oriented electrical steel sheet excellent in machinability, for example, in Japanese Patent Publication No. 54-11769, a steel sheet utilizing notch effect or lubrication effect of graphite instead of free-cutting elements such as Pb and S. Is proposed. Also, Japanese Patent Publication No. 56-34616 discloses that
It has been reported that the addition of a large amount of Mn can improve the machinability without deteriorating the iron loss characteristics. However, none of the above steel sheets has sufficient machinability, and improvement thereof has been desired.

[0004]

SUMMARY OF THE INVENTION The present invention advantageously meets the above-mentioned requirements and impairs various characteristics other than the machinability required for electromagnetic steel sheets, such as magnetic characteristics, punchability and weldability. The purpose is to propose a non-oriented electrical steel sheet with further improved machinability without worries.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors manufactured a rotor by punching a plate using several tens of kinds of steel materials having different composition and used them for actual cutting. By doing so, the relationship between the composition of the steel and the machinability was investigated. As a result, the invention steel having the composition as described below was completed.

That is, the present invention is C: 0.007% or less,
Si: 0.5% or less, Al: 0.1% or less and P: 0.1% or less, Mn, Mn: 0.3% or less, and the mixed amount is
It is a non-oriented electrical steel sheet with excellent machinability that contains 0.01% or less of S in the range satisfying the following formula 20 ≤ Mn / S ≤ 80, and the balance is substantially Fe composition. is there.

[0007]

The reason why the component composition of the steel material is limited to the above range in the present invention will be described below. C: 0.007% or less When C is contained in a large amount, not only the magnetic properties are adversely affected but also the hardness of the steel material is increased. Therefore, the C content is preferably low, and 0.007% or less, preferably 0.005% or less.

Si: 0.5% or less Si has the effect of increasing the specific resistance of the steel material and reducing the iron loss, so it is contained according to the target magnetic property level of the steel material, but the content is 0.5%. If it exceeds the above value, the saturation magnetic flux density decreases, the desired high magnetic permeability cannot be obtained, and the manufacturing cost rises, which does not meet the purpose of low-cost mass production, so the content was made 0.5% or less.

Al: 0.1% or less Al content is preferably as small as possible from the viewpoint of machinability, and if the content exceeds 0.1%, machinability deteriorates sharply, so the upper limit was made 0.1%.

P: 0.1% or less P effectively contributes to the improvement of punching workability, and in particular, like the steel sheet of the present invention, it is punched into a predetermined shape by a die before lamination and cutting. It is useful for steel sheets. For that purpose, addition of 0.05% or more is preferable,
If it exceeds 0.1%, the hardness of the steel plate will increase too much, similar to Mn.
The machinability is adversely affected, so the upper limit was made 0.1%.

Mn: 0.3% or less Mn is a useful element that reduces the adverse effect of S inevitably mixed on the magnetic characteristics. In order to exert this effect, the ratio to the amount of S is 20 ≦ Mn / S ≦. It is important to contain it within a range that satisfies the 80 relationship. I mean,
If the Mn / S ratio is less than 20, MnS is finely precipitated in the steel after hot rolling, and the grain growth property during annealing after cold rolling is significantly impaired. On the other hand, if it exceeds 80, or if the above Mn
Even if the Mn / S ratio is satisfied, it was confirmed that if the Mn content exceeds 0.3%, the hardness of the steel sheet increases due to the effect of Mn, which adversely affects the machinability. 80
The content of Mn is 0.3% or less.

S: 0.01% or less As described above, S is a harmful element that adversely affects the magnetic properties, so it is desirable to reduce its incorporation as much as possible, but S content of 0.01% or less is acceptable.

[0013]

【Example】

Example 1 C: 0.003%, Si: 0.12%, P: 0.05%, Mn: 0.15% and S: 0.003% were the basic components, and Al was 0.002%, respectively.
%, 0.080%, 0.12% and 0.20% contained in four types of steel slabs, after subjecting them to normal hot rolling, cold rolling and annealing treatment, to obtain cold rolled sheets with a final thickness of 0.50 mm, An insulating coating was applied. Then, these steel plates were slit, punched into a predetermined shape, laminated, and die-cast with aluminum to obtain a test piece for investigation of machinability. After that, each sample was cut at a cutting speed of 190 m / min, depth of cut: 0.3 mm, and feed:
The cutting was performed using a superalloy-based cutting tool under the condition of 0.2 mm / rev. The material of the cutting tool is WC, TiC, and TaC that are generally used for cutting the outer periphery of laminated electromagnetic steel sheets, manufactured by a sintering method using Co as a binder. The machinability was evaluated by the amount of wear on the flank of the bite tip after cutting for a certain period of time. The obtained results are shown in FIG.

As is clear from the figure, the Al content is 0.10.
%, The wear of the cutting tool sharply increased, while the wear of Al contents of 0.10% or less did not increase so much even after long-term cutting.

Example 2 C: 0.003%, Si: 0.12%, P: 0.05%, Al: 0.002%
And S: 0.004% as the basic component, Mn of 0.10 each
%, 0.25%, 0.40% and 0.80% of the four types of steel slabs were treated in the same manner as in Example 1 to produce a non-oriented electrical steel sheet with an insulating coating. Then, also in the same manner as in Example 1, the results of investigating the machinability are shown in FIG.
As is clear from the figure, in the steel material containing a large amount of Mn exceeding the upper limit of the present invention, the wear amount of the cutting tool increased with the cutting time, while the Mn content was 0.30% or less. The wear amount did not increase so much even after cutting for a long time.

Example 3 C: 0.003%, Si: 0.12%, Al: 0.002%, Mn: 0.10%
And S: 0.002% as a basic component, P is 0.05
%, 0.09%, 0.12%, and 0.15% of the four types of steel slabs were treated in the same manner as in Example 1 to produce a non-oriented electrical steel sheet with an insulating coating. Then, also in the same manner as in Example 1, the results of investigating the machinability are shown in FIG.
As is clear from the figure, in the steel material containing a large amount of P exceeding the upper limit of the present invention, the wear amount of the cutting tool increased with the cutting time, while the P content was 0.10% or less. The wear amount did not increase so much even after cutting for a long time.

[0017]

As described above, according to the present invention, the machinability can be remarkably improved without deteriorating other characteristics, and the low-cost mass production enables the inexpensive supply of the non-oriented electrical steel sheet. Can be achieved.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the cutting time of steel materials and the amount of tool wear, using the Al content as a parameter.

FIG. 2 is a graph showing the relationship between the cutting time of steel materials and the amount of tool wear, using the Mn content as a parameter.

FIG. 3 is a graph showing the relationship between the cutting time of steel materials and the amount of tool wear, using the P content as a parameter.

Claims (1)

[Claims] 1. C: 0.007 wt% or less, Si: 0.5 wt% or less, Al: 0.1 wt% or less, and P: 0.1 wt% or less, and Mn is mixed with Mn: 0.3 wt% or less. The machinability is characterized in that the ratio of S to the amount of S suppressed to 0.01 wt% or less is contained in a range satisfying the following formula 20 ≤ Mn / S ≤ 80, and the balance is substantially Fe composition. Excellent non-oriented electrical steel sheet.