JPH0331467A - Production of steel material for member absorbing vibration energy - Google Patents

Abstract

PURPOSE:To obtain a steel material suitable for use as a brace material absorbing external energy such as deformation or vibration energy by hot working and cooling steel contg. specified amts. of C, Si, Mn, P, S, Al, N, etc., under prescribed conditions. CONSTITUTION:Steel consisting of, by weight, <=0.004% C, <=0.1% Si, <=0.1 5% Mn, <=0.015% P, <=0.01% S, 0.5-2% sol. Al, <=0.005% N, <=0.005% oxygen and the balance Fe is refined, heated to 950-1300 deg.C, hot worked at >=950 deg.C finishing temp. and cooled at a cooling rate below the air cooling rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a steel material for vibration energy absorbing members used in structures that require a vibration damping function, among other steel materials for construction. It is.

[Prior art wjK] Efforts have been made in various places to actively reduce deformation and vibration of steel structures due to external forces, thereby increasing the added value of the structures.

For example, Japanese Utility Model Application Publication No. 19760/1983 discloses an idea regarding an oscillating wall characterized by using lead, which has excellent damping performance, as an energy absorbing material.

Mata, #II Geotechnical Engineering Papers Voa, 34B (198
(March 1980), the core material was made of low-strength steel in order to obtain damping performance.

A study on an unbonded place where buckling was prevented by steel pipe concrete is presented.

[Problems to be Solved by the Invention] However, this problem is shown in the invention disclosed in Japanese Utility Model Application Publication No. 19760/1983. Energy absorbing materials made of lead have low breaking strength, and there is concern that it will be difficult to apply them directly to places, for example.

On the other hand, the energy-absorbing steel materials used in the places shown in the above-mentioned Structural Engineering Papers have a low yield stress, but their breaking strength is higher than that of ordinary industrial pure steel. When a place material undergoes plastic deformation in an environment subjected to tension and compression and absorbs external energy that causes deformation and vibration, for example, when it undergoes repeated plastic deformation due to repeated earthquakes, processing There is a concern that the hardening will increase the yield stress, leading to a decrease in energy absorption ability.

In addition, when using steel materials with insufficient breaking strength for places, increasing the cross-sectional area unnecessarily to avoid buckling during compression will endow the structure with excessive yield strength. The structure must be made of strong steel pipe concrete to prevent buckling.

As mentioned above, among materials that also have mechanical properties as structural materials, materials with low yield stress, low breaking strength, and high elongation ability are advantageous for repeated loading and buckling, and have good deformation. - It can be used as a vibration energy absorbing material, but such a material has not yet been developed.

[Means for Solving the Problems] The inventors have made earnest efforts to solve the above-mentioned problems. And to obtain a material that has mechanical properties as a structural material and has excellent damping performance.

By adding Al to industrially pure iron, which is known as a soft material, the ferrite crystal grains become coarser, lowering the yield stress and achieving 1. The aim was to reduce the breaking strength.

AQ is a ferrite phase stabilizing element, and by adding it to pure iron, it can significantly increase the transformation temperature of ferrite.
Alternatively, it has the effect of forming a single phase of ferrite. Therefore,
By adding 0,5 wt, fs or more of Aρ,
It is possible to form a ferrite structure at a high temperature of 950° C. or higher, and when hot working is completed at a high temperature, growth of ferrite crystal grains can be promoted in the cooling process. In addition, the growth of ferrite crystal grains can be similarly promoted by separately performing heat treatment at 950°C or higher after hot working. As a result, abnormal grain growth of ferrite crystal grains occurs, and a ferrite structure with a grain size exceeding 1 m can be obtained.

In other words, by including AQ, it is possible to coarsen the crystal grains and to have a softening effect on the solid solution AΩ itself, but due to the synergistic effect of these, it is possible to achieve a low yield within the range of mechanical properties that can be used as a structural material. It was discovered that it is possible to obtain a material with stress and tensile strength. This invention was made based on the above-mentioned findings.

The gist of this invention is as follows.

(1) C0,004wt,% or less.

Si 0.10wtJ or less, Kn 0015wt,% or less, P 0.015wt0% or less, SO,0IOwt% or less, So Q A El: 0.5ON2.0wt. %,
N: 0,005s+t, % or less; Oxygen: 0.005wt, % or less; and the balance: substantially Fa. A steel slab or slab is heated to a temperature of 950 to 1300°C, and then the process is finished. Method for manufacturing a steel material for vibration energy absorbing members (2) characterized by hot working at a temperature of 950°C or higher and then cooling at a cooling rate lower than air cooling after the hot working is completed C: 0.004wt ,%below.

Si: 0.10wtJ or less5 Kn: 0.15wt, % or less.

p: 0.015%+1. Below z.

S: 0,010wt, x or less.

SoQ A11: 0.50-2.0wt. %, N
: 0.005 wt, % or less, Oxygen: 0,005 wt, % or less, and the balance substantially Fe: A steel billet or slab is heated to a temperature of 950 to 1300°C, and then hot worked. 1. A method for manufacturing a steel material for a vibration energy absorbing member, characterized by subjecting the steel material to a final heat treatment at a temperature of 950 to 1300° C. after hot working.

Next, the reason why the composition of the steel of the present invention is limited as described above will be described below.

(1) C (Carbon) C is an element that increases strength through solid solution or carbide formation. Therefore, from the purpose of the present invention, it is desirable to reduce it as much as possible, but it is extremely difficult to reduce it in industrial production. is difficult and leads to extremely high costs;
In order to increase the transformation temperature by adding AΩ, which will be described later,
If the C content is not kept low, the required amount of AJ will increase, which will eventually lead to solid solution strengthening of AΩ, so for this reason as well, the C content should be kept low. That is desirable, therefore.

0, where the C content is below the solid solubility limit of C at room temperature;
004wt,% or less.

(2) Si (Silicon) Si has the effect of increasing the transformation temperature when added by itself; in the present invention, this effect is satisfied by the addition of Afi-, which will be described later.

Rather than the above-mentioned effect of adding Si,
There is a concern that strength will increase due to solid solution strengthening. Therefore, the Sl content was set to 0.1 wtJ or less.

(3) Mn (manganese) Like Mn-8+si, it is a solid solution strengthening element, and Mn is used as much as possible.
Although it is desirable to reduce the Mn content, an extreme reduction in the Mn content will lead to high costs, so the Mn content should be 0.15w.
It was set to t% or less. However, since Mn has the effect of preventing hot embrittlement caused by S, the Mn content is preferably at least 10 times the S content.

(4) P, S (phosphorus, sulfur) P and S are contained as impurity elements. Therefore, it is desirable to reduce the P content as long as it does not lead to increased costs. Therefore, the P content is 0.015wt,
% or less, S content is 0.01wt.

% or less.

(5) A consideration (aluminum) /l is an element that is a key element of the present invention as described above. The capsule causes the fixation of solid solution N, the agglomeration and coarsening of AQN particles, and the rise in transformation temperature, which promotes the coarsening of ferrite crystal grains in the high temperature range made possible by the expansion of the ferrite region, and furthermore, the formation of solid solution AM. In the present invention, it is an essential element in order to reduce the strength because it has a softening effect. However, when the +ll content is SoΩ10, 0
, less than 5 wt%, the desired effects described above cannot be obtained.

On the other hand, when the AΩ content is 5oflAfi, 2, O
Exceeding yt,% leads to the effect of solid solution strengthening, therefore,
The AQ content is 0.5 to 2. Owt
% range.

(6) N (Nitrogen) N has the effect of increasing the strength by forming a solid solution or nitride in Fa. In addition, in order to make the contained Afi exist as effective solid solution Am, it is desirable that the amount of AflN particles generated is small. Therefore, the N content is 0.
．． 005wt,% or less.

(?) O (oxygen) Oxygen is an impurity element that generates nonmetallic inclusions. The oxygen content was 0.005 wt.% or less.

Next, the manufacturing conditions of this invention steel material will be described below.

Regarding hot rolling conditions, very normal hot working conditions were adopted, and the heating temperature was 950 to 13 oO<0>C. However, the first
In the embodiment (invention according to claim 1), in order to ensure coarse ferrite crystal grains, the processing end temperature is set to 9.
The temperature was 50°C or higher. Furthermore, in cooling after hot working, it is necessary to promote the growth of crystal grains in the cooling process after working, so it is necessary to cool at a cooling rate lower than air cooling.

On the other hand, in the second embodiment (invention according to claim 2) in which heat treatment is finally performed, there is no restriction on the hot working end temperature as described above, but after hot working, the temperature is 950 to 13
Heat treatment is performed at a temperature of 00°C. That is, even if the hot working end temperature is less than 950° C., the same effect can be obtained by performing heat treatment after hot working. As the heat treatment conditions, in order to promote the growth of ferrite crystal grains at a temperature of 950°C or higher, it is preferable to hold the heat treatment for at least 30 minutes or more in consideration of the heat capacity of the material.
Content: O,001wt0%, 5oAAQ content: 11
The steel of the present invention with t0% has a single phase of ferrite, and has 110
Heat treatment at extremely high temperatures above 0°C.

This is extremely effective for the growth of ferrite crystal grains. However, heat treatment in a temperature range exceeding 1300° C. is difficult and increases costs.

The heat treatment temperature was 950 to 1300°C.

As described above, with the chemical composition and manufacturing conditions according to the present invention, it is possible to obtain a steel material with low yield stress and tensile strength and high elongation ability, that is, excellent deformation and vibration energy absorption performance.

Next, the present invention will be explained in more detail with reference to Examples.

[Example] After melting inventive steels A-F having chemical compositions within the scope of the present invention and comparative steels G and H having chemical compositions outside the scope of the present invention shown in Table 1, First, this steel ingot was heated to 1200°C, and then,
Hot rolling was carried out at a rolling end temperature of 1100° C. to form a plate with a thickness of 15 cm.

Additionally, some of the steels were heat treated (annealed) at a temperature of 1100°C. In addition, the transformation points of these IIA to H were investigated when the temperature was raised to a temperature of 1300°C at a heating rate of 0.5°C/sec, and the results are also shown in Table 1'. The results show that the inventive steels A-F have a ferrite single phase or a ferrite transformation point higher than that of comparative steels G and H.
A tensile test consisting of the following was carried out on the above-mentioned inventive steels A-F and comparative steels G and H, which were molded to a plate thickness of 15 cm and showed a high temperature compared to the above. The results are shown in Table 2.

Tensile test After hot rolling or heat treatment after rolling, a test piece with a parallel part diameter of 6 m and a parallel part length of 16 to 40 cm was cut out from the center of the plate thickness, and a tensile test was performed on this test piece to determine the yield stress. Or 0.2% yield strength.

And the tensile strength was examined.

As is clear from Tables 1 and 2, 1 inventive steel A has 11
Inventive example &1, which was annealed (heat treated) at 00°C, has a single phase of ferrite due to the low carbon content and AQ addition, so by annealing at a high temperature, grain refinement due to transformation from austenite to ferrite can be achieved. Rather, by annealing at a high temperature of 1100° C., significant coarsening of the ferrite grain size to 21 or more is achieved, and low yield stress and low tensile strength are achieved.

Inventive example NQ2, in which the inventive steel B was not heat-treated at high temperature in an as-rolled state, had higher strength than inventive example Nα1, but had lower strength characteristics than comparative examples P&18, which will be described later. ing.

In both examples &5 of the present invention, in which the as-rolled steel is not heat-treated at a high temperature, the ferrite is made into a single phase or the transformation point is raised to a high temperature by adding A base, and the production method of the present invention is adopted. As a result, lower strength is achieved.

In contrast, comparative steel G, which is equivalent to industrial pure iron, has a
Comparative Example 7, same comparative steel G which was annealed (heat treated) at ℃
In Comparative Example 8, which was not heat-treated at a high temperature in the as-rolled state, not only Comparative Example 8, but even Comparative Example 7, which was annealed at a temperature of 950°C or higher, showed no significant decrease in strength. I can't.

Comparative Steel H, which corresponds to one of the steel materials commonly used for conventional place materials and which greatly deviates from the chemical composition of the present invention, was not heat-treated at high temperature in the as-rolled state.Comparative Example Na9 steel has high yield stress and high tensile strength, and its properties as a steel material for vibration energy absorbing members are difficult to expect except in areas where the level of external force is excessive.

In addition, all the examples of the present invention shown in the above-mentioned examples are 40%
Therefore, there is no problem with ductility when applied to place materials, etc.

[Effects of the Invention] As explained above, according to the present invention, a steel frame building has low yield stress, low tensile strength, and high elongation capacity. Suitable for place materials that absorb external energy such as deformation and vibration.

The industrially useful effect of obtaining a steel material for vibration energy absorbing members is brought about.

Originator: Nippon Kokan Co., Ltd.

Claims (1)

[Claims] 1 C: 0.004wt. % or less, Si: 0.10 wt% or less, Mn: 0.15 wt% or less, P: 0.015 wt% or less, S: 0.010 wt% or less, SolAl: 0.50 to 2.0 wt%. %, N: 0.005 wt% or less, Oxygen: 0.005 wt% or less, and the balance: substantially Fe, is heated to a temperature of 950 to 1300°C, and then finished. Method 2 for producing steel materials for vibration energy absorbing members, characterized by hot working at a temperature of 950° C. or higher, and then cooling at a cooling rate lower than air cooling after the hot working is completed C: 0.004 wt. % or less, Si: 0.10 wt% or less, Mn: 0.15 wt% or less, P: 0.015 wt. % or less, S: 0.010wt. % or less, SolAl: 0.50-2.0wt. %, N: 0.005 wt% or less, Oxygen: 0.005 wt% or less, and the balance substantially Fe, is heated to a temperature of 950 to 1300°C, and then hot A method for manufacturing a steel material for a vibration energy absorbing member, characterized in that the steel material is processed, and then, after the hot working is completed, a final heat treatment is performed at a temperature of 950 to 1300°C.