JPH0734198A - Steel for high strength chain excellent in wear resistance - Google Patents

Abstract

PURPOSE:To obtain steel for high strength chain excellent in wear resistance and corrosion resistance by subjecting high Mn nonmagnetic steel with an austenitic structure contg. a specified amt. of Mn to cold working and regulating its proof stress and strength. CONSTITUTION:High Mn nonmagnetic steel having a compsn. contg., by weight, 10 to 30% Mn, furthermore contg., at need, one or more kinds among 0.1 to 6% Ni, 13 to 20% Cr and 0.1 to 2% Mo and moreover contg. 0.15 to 0.5% N and constituted of an austenitic structure is subjected to cold working. By this cold working, its 0.2% proof stress is regulated to >=588N/mm<2> and tensile strength to >=882N/mm<2>. In this way, the steel for a high strength chain usable over a long period even in a severe environment can be obtd.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is useful as a material for a link chain or the like which is used in a place where it is immersed in cooling water at a relatively high temperature and much dust, such as a chain for ash scraping in a coke oven. The present invention relates to a chain steel material, and more particularly to a chain steel material having sufficient strength even under the high temperature environment as described above and exhibiting good wear resistance and corrosion resistance. Note that the steel material for chains of the present invention is meant to include a steel material for joint fittings in which a ring chain and a metal plate are continuous in a jig to be described later, but hereinafter collectively referred to as steel material for chains.

[0002]

2. Description of the Related Art During the operation of a coke oven, it is necessary to continuously scrape out the ash accumulated at the bottom of the oven and discharge it to the outside. For such ash scraping work, a jig for moving a metal plate by a chain is generally used. At this time, the environment to which the jig is exposed is a harsh environment in which the temperature is a high temperature of about 600 ° C., various kinds of dust are present, and the jig is further immersed in cooling water.

Conventionally, many rolled round steels such as 15B24 and SCM420 have been used as a material of a chain used for a jig for ash scraping, and a predetermined strength and It is designed to give toughness. However, 15B24 and S
If a chain made of steel such as CM420 is used in the harsh environment as described above, the link strength and wear amount are likely to increase due to the decrease in material strength due to exposure to high temperatures, and The growth of the total length will be large, and it will be forced to replace it in a short period of time. As a result, there arises a problem that maintenance costs increase.

[0004]

The present invention has been made in order to solve these technical problems, and its purpose is to be used for a long period of time even under the severe environment as described above. It is to provide such steel materials for chains.

[0005]

According to the present invention which has achieved the above object, cold working is performed on a high Mn non-magnetic steel containing 10 to 30% by weight of Mn and having an austenitic structure. It is a steel material for a high-strength chain, which is characterized in that it is adjusted to have a 0.2% proof stress of 588 N / mm ² or more and a tensile strength of 882 N / mm ² or more.

[0006]

When the conventional chain is used as a material for 15B24 or SCM420 in the above-mentioned severe environment, it is heated to about 600 ° C once because it is a steel material that maintains its strength by quenching and tempering. As a result, the tempering temperature becomes higher than the tempering temperature, resulting in a decrease in strength. Therefore, it expands or deforms in a short period of time. Further, it is considered that the elongation and deformation are caused by insufficient strength at high temperature and poor wear resistance. Therefore, we examined from various angles a steel material for chains that has excellent high-temperature strength and wear resistance and can withstand use in the above-mentioned environment. As a result, it has been found that a steel material obtained by strengthening a high Mn non-magnetic steel by cold working satisfies the above-mentioned required characteristics and is optimal as a steel material for chains. That is, high-Mn non-magnetic steel is cold-worked to a level of 0.
With a 2% proof stress of 588 N / mm ² (60 kgf / mm ² ) or more and a tensile strength of 882 N / mm ² (90 kgf / mm ² ) or more, 0.2% proof stress is obtained even in a high temperature atmosphere of about 600 ° C. 294 N / mm ² or more, the tensile strength can be maintained 450 N / mm ² or more, the heat resistance be cooled after the heating is excellent, strength reduction holds a little high strength. Also,
Due to repeated continuous operation at 600 ° C and water cooling, red rust occurs and corrosive wear occurs in the conventional chain, but this steel material has excellent corrosion resistance and can reduce corrosive wear. It was found that such a steel material is the most suitable for the above chains,
The present invention has been completed.

Further, since Mn has a function of increasing the work hardening ability in cold working, hardening occurs due to work hardening in the sliding friction portion at the initial stage of use, and there is an effect that the amount of wear thereafter is reduced. Further, Mn is an element effective in stabilizing the austenite structure, the steel material is non-magnetic in the austenite-phase, and it also exerts an effect of making it difficult for dust such as iron powder, which is harmful to wear of the steel material, to adhere.

In order to exert the above effects, the Mn content of the steel material of the present invention needs to be 10% by weight or more, but if it is contained excessively, the hot workability is remarkably deteriorated. It should be kept to 30% by weight or less as it is substantially difficult to manufacture. Further, the content of C is not particularly limited, but as the content increases, the cuttability deteriorates, so the content is preferably 0.3% by weight or less.

By the way, the steel material of the present invention is used under special conditions, and in some cases, better corrosion resistance is required. In such a case, it is effective to add Ni, Cr, Mo, etc., but since all of these elements are expensive, they may be selectively added individually or in combination as required. . In order to exert the corrosion resistance improving effect by these elements, it is necessary to add Ni in an amount of 0.1 wt% or more, Cr in an amount of 13 wt% and Mo in an amount of 0.1 wt% or more. The effect is saturated, so Ni
Should be 6 wt% or less, Cr should be 20 wt% or less, and Mo should be 2 wt% or less. Further, N is an element effective for stabilizing the austenite structure and contributes to the strength improvement. Therefore, when higher strength is desired, N is set to 0.
It is effective to contain 15% by weight or more. However, N
The effect is saturated with 0.5% by weight.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any design changes made in view of the spirit of the preceding and the following will not be considered. It is included in the technical scope.

[0011]

Example Steels having the chemical composition shown in Table 1 (No. 1 to 6)
Was melted in a high frequency melting furnace to obtain a steel ingot of 150 kg in each case.

[0012]

[Table 1]

From the obtained steel ingot, the diameter was 28 by forging.
mm steel bars were manufactured, and for Nos. 1 to 3 (Example) and No. 6 (Comparative Example), steel bars having a diameter of 25 mm (working ratio: 20%) were manufactured by cold drawing after solution heat treatment. No.
For Nos. 4 and 5 (Comparative Examples), steel bars having a diameter of 28 mm were subjected to quenching and tempering treatment as they were, and used as test materials. Then, a tensile test (tensile strength, 0.2% proof stress) and an abrasion test were performed on each test material.

FIG. 1 shows the room temperature to 600 ° C. of each test material.
2 is also a graph showing the 0.2% proof stress. As is clear from these results, it is understood that the examples of the present invention have higher strength on the high temperature side than the comparative examples.

On the other hand, the abrasion test was carried out by a rotary friction disc system as shown in FIG.
The wear resistance was evaluated by the amount of wear of the mm round bar). The results are shown in FIG. 4, which are those of the embodiment of the present invention (No.
The wear amount of 3) is 1/2 to 1/7 of that of the comparative example (No. 4 to 6).
It can be seen that the excellent wear resistance is exhibited.

[0016]

EFFECTS OF THE INVENTION The present invention is constructed as described above, and can realize a steel material excellent in strength and wear resistance at high temperatures, and this steel material can be used for a long time even when used as a chain in a severe environment. It will be possible.

[Brief description of drawings]

FIG. 1 is a graph showing the tensile strength of each test material from room temperature to 600 ° C.

[Fig. 2] Fig. 2 is a graph of 0.
It is a graph which shows 2% yield strength.

FIG. 3 is a diagram illustrating a rotary friction disc method.

FIG. 4 is a bar graph showing the amount of wear of each test material in comparison.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Toyama 2 Nadahama Higashi-cho, Nada-ku, Kobe-shi, Hyogo Stock Company Kobe Steel Works, Kobe Steel Works (72) Inventor Toyoji Fukamizu 13 Seaside-cho, Kishiwada-shi, Osaka Showa Machinery Within Shoji Co., Ltd.

Claims (3)

[Claims] 1. A 0.2% proof stress: 588 N / mm by cold working a high Mn non-magnetic steel containing 10 to 30% by weight of Mn and having an austenitic structure.
^A steel material for a high-strength chain with excellent wear resistance, characterized by being adjusted to ² or more and tensile strength: 882 N / mm ² or more. 2. Further, Ni: 0.1 to 6% by weight, Cr:
The steel material for a high-strength chain according to claim 1, containing one or more selected from the group consisting of 13 to 20% by weight and Mo: 0.1 to 2% by weight. 3. The steel material for a high-strength chain according to claim 1 or 2, which further contains N: 0.15 to 0.5% by weight.