KR20140119216A

KR20140119216A - High manganese alloy and the manufacturing method for high manganese alloy

Info

Publication number: KR20140119216A
Application number: KR1020130032526A
Authority: KR
Inventors: 김정철
Original assignee: 주식회사 우진
Priority date: 2013-03-27
Filing date: 2013-03-27
Publication date: 2014-10-10

Abstract

The present invention relates to a high-strength high-manganese steel comprising 15 to 20% Mn, 0.2 to 0.8% C, 0.1 to 0.5% Si, 0.1 to 0.6% Ti, and the balance Fe and other unavoidable impurities, It is technically essential.
As described above, according to the present invention, it is possible to manufacture high manganese steel showing stable toughness in the sintering region while taking advantage of the characteristics of the conventional anti-vibration alloy. That is, high manganese steel capable of absorbing earthquake energy due to plastic deformation even at a small load (i.e., low yield strength) can be produced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high manganese steel and a method for manufacturing the same,

The present invention relates to a high-strength high-manganese steel and a method for producing the same, and more particularly to a high-manganese steel having a high toughness, that is, not only a large stress required for fracture but also a large deformation to fracture, And a manufacturing method thereof.

Recently, the number of earthquakes has increased and the scale of damage has been increasing, and earthquakes in neighboring countries such as the earthquake in Japan (Fukushima Earthquake, 2011) have caused damages in Korea as well. In Korea, seismic design standards have been greatly enhanced.

One method that can be reflected in seismic design is to use a damper. Among them, the hysteretic damper is effective in designing the firing corresponding to an earthquake, and the most common one is a steel damper. On the other hand, an oil damper or the like is most commonly used in designing an elasticity effective for a wind load. This is because there is almost no material development that can act as a large damper under the elastic region as the steel material.

Therefore, the Fe-Mn based anti-vibration alloy (Korean Patent No. 10-0107044) developed by Woojin Co., Ltd. has a very excellent vibration energy absorbing ability under the elastic region, so that the oil damper can be substituted under the elastic region. However, when the repeated load acts on the Fe-Mn-based vibration damping alloy in the firing region, the ε-martensite transforms into the stress-induced α 'martensite. As a result, a number of fragile α 'martensite sites are formed and breakage occurs. In other words, since the fracture occurred due to cyclic loading, there was an inadequate plane in the plastic earthquake.

Also, SS400 steel used as a conventional steel damper is very insufficient to absorb seismic energy because its toughness is very small as in the hysteresis loop of Fig.

Another problem is that the damper must have the capability of absorbing the earthquake energy due to plastic deformation even at small loads (i.e., low yield strength). However, it is difficult to use the conventional Al alloyed steel as a damper because the yield strength is too high as 600 MPa or more.

The degree of toughness of material destruction is called toughness, which is expressed as the energy per unit volume applied to the destruction. This means not only a large stress required for fracture but also a large amount of deformation leading to fracture and a large absorption energy. Materials with strong toughness are more suitable for earthquakes. As described above, the alloy steel of the related art has a small toughness and has a weak performance of absorbing the seismic energy. Therefore, it is urgent to develop a technique for a high-strength steel material.

Korean Patent Registration No. 10-0107044 1996.5.16.

An object of the present invention is to provide a high manganese steel (Fe-Mn alloy steel) having a stable toughness in a sintering region while taking advantage of the characteristics of a conventional anti-vibration alloy and a method of manufacturing the same.

Another object of the present invention is to provide a high manganese steel having high manganese steel having austenite structure and capable of absorbing earthquake energy due to plastic deformation even at a small load (i.e., low yield strength), and a method for manufacturing the same.

According to an embodiment of the present invention to achieve the above object, there is provided a method of manufacturing a semiconductor device, which comprises 15 to 20% of Mn, 0.2 to 0.8% of C, 0.1 to 0.5% of Si, 0.1 to 0.6% of Ti, And other unavoidable impurities.

At this time, the high manganese steel may be made of an austenite structure.

In addition, the high tenacity high manganese steel may have a characteristic of a yield strength of 250 to 350 MPa.

In addition, the present invention provides a method for producing a high-strength high-manganese steel in which a molten high-manganese molten metal is cast, slowly cooled to make an ingot, and then subjected to homogenization heat treatment and hot rolling.

At this time, the high manganese steel melt may contain 15 to 20% of Mn, 0.2 to 0.8% of C, 0.1 to 0.5% of Si, 0.1 to 0.6% of Ti, and the balance Fe and other unavoidable impurities.

In addition, the casting can be done at 1,450 ~ 1,650 ℃.

The homogenization heat treatment can be performed at a temperature of 900 to 1,200 ° C for 2 to 4 hours.

The hot rolling may be performed at a temperature of 900 to 1,100 ° C.

As described above, according to one embodiment of the present invention, it is possible to manufacture high manganese steel showing stable toughness in the sintering region while taking advantage of the characteristics of the conventional anti-vibration alloy. That is, high manganese steel capable of absorbing earthquake energy due to plastic deformation even at a small load (i.e., low yield strength) can be produced.

FIG. 1 is a hysteresis loop comparing relative values of SS400 steel alloy, anti-vibration alloy, and high manganese steel (Fe-Mn-C alloy steel) of the invention.
2 is a graph showing the amount of austenite according to the content of carbon (C).
FIG. 3 is a result of analyzing skeleton curve test results of conventional steel 1 and inventive steel 1 (containing 0.5 wt% C) to compare the absorption energy of the steel.
4 is a result of analyzing skeleton curve test results of conventional steel 2 and inventive steel 2 (containing 0.6 wt% C) to compare the absorption energy of the steel.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4 attached hereto. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments are provided to explain the present invention to a person having ordinary skill in the art to which the present invention belongs.

The present invention relates to a high-manganese steel (Fe-Mn-C alloy steel) having excellent toughness, and is excellent in an alloy steel and a steel damper material excellent in tensile strength of 800 MPa or more, yield strength of 300 MPa or less, elongation of 60% Lt; / RTI > Therefore, the present invention is characterized by the high manganese steel which has the characteristics of the conventional anti-vibration alloy and exhibits stable toughness in the sintering region and its manufacturing method.

First, the reason for limiting the components of the present invention will be described. (Hereinafter, the% by weight is simply referred to as%).

Carbon (C) is an element added for strength improvement. If the content of C is less than 0.2%, there is a problem that the stability of the austenite decreases and the strength decreases. When the content of C is more than 0.8%, the weldability decreases and the second phase sharply increases and the workability deteriorates. Therefore, the content of C is limited to 0.2 to 0.8%.

Manganese (Mn) is an austenite stabilizing element that increases the hardenability and increases the strength. In the present invention, at least 15% of manganese should be contained in order to obtain a stable austenite structure, but when it exceeds 20%, weldability is lowered and inclusions are formed. Therefore, the content of Mn is limited to 15 to 20%.

When the content of silicon (Si) is less than 0.1%, the fluidity of alloy steel is lowered. When the content of silicon (Si) is more than 0.5%, the alloy steel becomes weak, and the content of Si is limited to 0.1-0.5%.

When titanium (Ti) is added, it is added to improve the weather resistance by forming a Ti oxide film. However, if it is 0.6% or more, TiC carbide is excessively formed, and the austenite stabilization is deteriorated, and the content of Ti is limited to 0.1 to 0.6%.

In one embodiment of the present invention, the high manganese steel comprises the above components and consists of the remainder Fe and other unavoidable impurities. If necessary, further alloying elements may be added to enhance the properties of the present high manganese steel and alloying elements not disclosed in the examples of the present invention may be added, which is not interpreted to be excluded from the scope of the present invention.

On the other hand, as one embodiment of the present invention, the high manganese steel is characterized by being made of an austenite structure, and the γ-solid solution containing carbon is called an austenite structure. The austenite structure generally has a hardness lower than that of martensite but has a larger elongation as compared with the tensile strength. The present invention is an austenitic high manganese steel excellent in toughness.

Hereinafter, a method for manufacturing a high-strength high manganese steel will be described in detail as an embodiment of the present invention.

The iron is charged into the melting furnace and melted, carbon and manganese are charged into the molten iron, and the element of the above composition is charged to prepare the molten iron.

The molten metal is cast at 1,450 to 1,650 DEG C to form an ingot after cooling. The ingot is subjected to a homogenization heat treatment at 900 to 1,200 ° C for 2 to 4 hours and then hot-rolled at a temperature of 900 to 1,100 ° C to obtain a high-strength high-manganese steel.

The reason for limiting the above-mentioned conditions in the embodiment of the present invention is as follows.

The reason for limiting the homogenization condition to 2 to 4 hours at 900 to 1,200 ° C is as follows.

As an embodiment of the present invention, since Mn, which is a main element of the alloy, segregates during casting, the cast ingot must be heated at a high temperature to diffuse a high concentration of manganese into a low concentration region to make the manganese composition uniform.

For this purpose, the ingot is heated at 900-1,200 ° C. When the temperature is lower than 900 ° C, the diffusion rate is slow and homogenization takes a long time, which increases the production cost. If the temperature is raised above 1200 ° C, the homogenization time can be shortened There is a risk that local melting of the grain boundaries in which Mn is segregated occurs during casting. Therefore, it is most appropriate to homogenize at 900 to 1,200 ° C for 2 to 4 hours.

The steel according to the present invention will act as an epoch-making material that can prevent the collapse of the building due to the seismic energy absorption due to the high fatigue when the earthquake occurs.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

After casting at a temperature of 1,450 ~ 1,650 ℃, the ingot was cooled to 900 ~ 1,200 ℃ for 2 ~ 4 hours and then hot rolled at 900 ~ 1,100 ℃. To produce an inventive steel.

Table 2 shows the tensile strength and elongation of the above-prepared inventive steels compared with the conventional tough SS400 and Fe-17% Mn.

River
Bell (% By weight) Mn C Si Ti Invention river 17 0.6 0.3 0.3

Steel species Tensile Strength (MPa) Elongation (%) Yield strength (MPa) Remarks SS400 400 20 - Conventional steel Fe-17% Mn 650 38 - Comparative steel Fe-17% Mn-0.6% C-0.3% Ti 800 75 300 Invention river

SS400 steel in Table 2 is a steel with tensile strength of 400 MPa or more, which contains C and Mn, has a composition of P of 0.05% or less and S of 0.05% or less.

Comparing the tensile properties, it can be seen that the tensile strength and the elongation of the invention steel are much higher than those of the conventional steel or comparative steel, as shown in Table 1. That is, the toughness is so large that it can be regarded as a suitable damper in preparation for an earthquake.

FIG. 1 is a hysteresis loop comparing relative values of SS400 steel alloy, anti-vibration alloy, and high manganese steel (Fe-Mn-C alloy steel) of the invention. As shown in FIG. 1, SS400 steel used as a conventional steel damper has a very small toughness. However, the inventive steel has a relatively high toughness compared to the existing steels.

FIGS. 3 and 4 show skeleton curve test results of conventional steel 1 and invented steel 1 (added 0.5 wt% C), conventional steel 2 and invented steel 2 (added 0.6 wt% C) The results are analyzed.

The energy absorbed by the skeleton curve represents the energy absorbed by the skeleton curve, which is 1.8 ~ 2.5 times better than that of the conventional steel.

The yield strength of the inventive steel is about 300 MPa, which is similar to that of conventional anti-vibration alloys. In general, when the tensile strength is 800 to 900 MPa, which is similar to that of the invention steel, the yield strength is 600 to 700 MPa which is about 70%. On the other hand, the inventive steel has high tensile strength but low yield strength and is suitable for seismic energy absorption.

Although the present invention has been described in detail by way of examples, other forms of embodiments are possible. Therefore, the technical idea and scope of the claims set forth below are not limited to the embodiments.

Claims

By weight, high manganese steel comprising 15 to 20% Mn, 0.2 to 0.8% C, 0.1 to 0.5% Si, 0.1 to 0.6% Ti, and the balance Fe and other unavoidable impurities.

The method according to claim 1,
Wherein the high manganese steel comprises an austenite structure.

3. The method according to claim 1 or 2,
The high manganese steel has a yield strength of 250 to 350 MPa.

Casting a molten metal containing 15 to 20% of Mn, 0.2 to 0.8% of C, 0.1 to 0.5% of Si, 0.1 to 0.6% of Ti, the balance Fe and other unavoidable impurities, in weight%;
Slowly cooling the cast high-manganese steel to make an ingot;
Subjecting the ingot to homogenization heat treatment; And
And subjecting the homogenized heat treated ingot to hot rolling.

5. The method of claim 4,
Wherein the casting is performed at 1,450 to 1,650 ° C.

5. The method of claim 4,
Wherein the homogenization heat treatment is performed at a temperature of 900 to 1,200 ° C for 2 to 4 hours.

5. The method of claim 4,
Wherein the hot rolling is performed at a temperature of 900 to 1,100 ° C.