JP2001342539A - Steel for high speed intermittent cutting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel excellent in tool life for a high speed intermittent cutting. SOLUTION: This steel contains Al: 0.04-0.20% and O: 0.0030% or below by mass % as steel components, wherein free cutting elements such as S, Ca, Pb, graphite, B, Te, Zr and the like, are not added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel to be subjected to cutting, and more particularly to a steel having an excellent tool life in intermittent high-speed cutting at 200 m / min or more.

[0002]

2. Description of the Related Art Free-cutting steel improves machinability by inclusions in the steel.
In a high cutting speed region such as S and Pb, a Ca-based composite oxide or the like is used. As an inclusion of the same type as MnS, MnS
Bi is used as an inclusion of the same system as e, MnTe, and Pb. In the case of a Ca-based composite oxide, it adheres to the cutting tool surface, prevents direct contact between the tool and the work material, and suppresses wear of the tool.

[0003] In recent years, there has been a movement to limit the use of Pb from the viewpoint of the global environment, and high-speed cutting has also been considered in intermittent cutting in order to improve efficiency.
Free-cutting steels having a new composition such as BN-added steel and graphite steel are disclosed in JP-A-60-174854 and JP-A-61-29195.
No. 5, JP-A-1-319965, JP-A-3-31951
64429, and the like.

Japanese Patent Application Laid-Open No. Sho 60-174854 discloses that Zr, a free-cutting element, is essentially added to increase the inoculating action of Zr on sulfides, to refine sulfides, and to improve machinability. Of 0.05 to 0.50%.
Japanese Patent Application Laid-Open No. 61-291955 essentially requires S and Te, which are free-cutting elements, and contains 2.0% or less of Al in order to improve the crystal structure and the heat treatment characteristics.

Japanese Patent Application Laid-Open No. 1-319651 discloses that BN which is a free-cutting element is indispensable. In order to promote precipitation of BN and fix oxygen in steel, Al is added in an amount of 0.001 to 0.001.
It contains 0.100%.

Japanese Patent Application Laid-Open No. 3-64429 aims to improve machinability at the time of interrupted cutting of tool steel.
The cutting speed is 150 mm / min.

[0007] Japanese Patent Application Laid-Open No. Hei 7-316732 requires graphite which is a free-cutting element as an essential element.
%contains.

[0008]

As described above, conventional free-cutting steels are particularly added with a free-cutting element in order to improve the machinability. Most of the areas that are considered to be slow or continuous cutting are considered.

The present invention has been made in view of the above points, and an object of the present invention is to provide a steel which does not contain a special free-cutting element and has excellent tool life in an intermittent high-speed cutting region of 200 m / min or more. And

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object and obtained the following knowledge.

(1) When the steel having a high Al content is intermittently cut at a high speed, Al oxide adheres to the tool surface and the tool life is improved. The deposit is Al in steel that is not oxide
However, during intermittent cutting, Al oxides are oxidized on the tool surface to form Al oxides. The Al oxides in steel have an adverse effect on machinability, but exhibit an effect of suppressing tool wear.

(2) It is effective to reduce the oxygen content in the steel in order to reduce the Al oxide in the steel, which reduces the machinability.

(3) When free-cutting elements such as Zr and Te are included,
The effect due to the adhesion of Al oxide cannot be sufficiently obtained. In the present invention, intermittent cutting refers to a case where a tool does not continuously contact a work material, such as milling, and includes a case where a product has a groove or the like even in the case of cutting.

The present invention has been further studied based on the above findings.

That is, the present invention provides: By mass%, Al: 0.04 to 0.20%, O: 0.
Intermittent high-speed cutting steel containing up to 0030%.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the components of the steel of the present invention will be described.

Al At the time of intermittent high-speed cutting, Al is added on the tool surface to prevent abrasion of the tool, and is added for deoxidizing steel. If it is less than 0.04%, the effect is not obtained. If it exceeds 0.20%, the effect is saturated.
0.20% or less.

O 2 O is converted into Al ₂ O ₃ by deoxidation and contained in steel.
Decreases machinability. Therefore, the lower the amount, the more preferable it is 0.0030% or less.

Free-cutting elements When free-cutting elements are added, the adhesion of Al oxide on the tool surface during intermittent high-speed cutting is hindered. In the present invention, the free-cutting elements are S, Ca, Pb, graphite, B, T
e, elements such as Zr, which have been conventionally used in free-cutting steels, with the addition amounts of S: 0.04% or less, Ca: 0.002
%, Pb: 0.03% or less, graphite, B: 0.005%
%, Te: 0.01% or less, Zr: 0.02% or less. Although the details of the adverse effects of the free-cutting elements are unknown, it is considered that the addition of the free-cutting elements changes the form of inclusions in the steel.

The present invention relates to the above-described A as a component composition of steel.
It suffices to satisfy the regulations on l, O and free-cutting elements,
The effect can be obtained with steel materials for cold forging, carbon steel for machine structures, low alloy steels, tool steels, bearing steels, and stainless steels. In particular, as a component composition, C: 0.01 to 1.2%, S
i: 0.05 to 1.0%, Mn: 0.3 to 2.0%,
S: 0.04% or less provides a desirable effect. The reasons for limiting the components will be described below.

C is added in an amount of 0.01% or more in order to secure strength. On the other hand, if it exceeds 1.2%, the amount of pearlite increases and the machinability deteriorates, so 0.01 to 1.2% is added.

Si Si is added as a deoxidizing agent in an amount of 0.05% or more. on the other hand,
If it exceeds 1.0%, the ferrite hardens and the machinability deteriorates, so 0.05 to 1.0% is added.

Mn Mn is added in an amount of 0.3% or more to secure strength. On the other hand, if it exceeds 2.0%, the machinability deteriorates due to an increase in the amount of pearlite, so 0.3 to 2.0% is added.

Since S S forms MnS and deteriorates mechanical properties,
0.04% or less. The effects of the steel of the present invention can be obtained regardless of the production method, and are not particularly limited.

[0025]

EXAMPLES Steel having the chemical composition shown in Table 1 was melted in a 150 kg vacuum melting furnace to form a 150 kg steel ingot, then hot forged (1200 ° C., 100 mm square), and normalized (850 ° C.,
After heating for 2 hours and air cooling), it was subjected to the test.

The cutting is dry intermittent cutting with a milling machine.
Table 2 shows the conditions. The flank wear is measured as the tool wear condition, and the time (minutes) until the wear width becomes 0.1 mm
Was evaluated. Table 3 shows the evaluation results.

According to Table 3, the steels of the present invention (Nos. 1 to 6)
At a cutting speed of 150 m / min, the comparative steel (No. 7 to
Although the tool wear suppression effect was almost the same as that of 9), it was 200
The high-speed cutting at m / min or more showed an excellent tool wear suppressing effect on the comparative steel.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

According to the present invention, the cutting speed is 200 m / m.
steel with excellent tool life in intermittent high-speed cutting of more than 1 inch, the efficiency of cutting is improved, and the steel composition is P
It is free from b, is considered for the global environment, and is extremely useful in industry.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuo Shirakami 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd.

Claims (1)

[Claims] 1. Al: 0.04 to 0.20 by mass%
%, O: 0.0030% or less.