JPH0553854B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing section steel used for structural members such as civil engineering, architecture, and marine structures. [Prior Art] As is well known, various types of shaped steel are used in large quantities for structural members such as civil engineering, architecture, and marine structures. In order to ensure safety, it is mandatory to apply sufficient fireproof coating, and building-related laws and regulations stipulate that the temperature of steel materials should not exceed 350℃ in the event of a fire. The above-mentioned fire-resistant coating can be applied to the surface of the steel material by spraying a spray material or felt based on slag wool, rock wool, glass wool, albestos, etc. A method of covering with a thin plate, such as a thin steel plate or a thin stainless steel plate, is adopted to prevent the shaped steel from losing its carrying capacity due to thermal damage in the event of a fire. Various methods have been proposed for the above-mentioned construction, but basically they are based on the publication published by Shokokusha Co., Ltd. on March 20, 1971 (steel-framed and reinforced concrete construction). As shown in Figure 6.21 on page 104, the commonly used method is to cover the steel with fibrous refractories or fireproof plates. [Problem to be solved by the invention] As mentioned above, section steel is a material with high strength and excellent economic efficiency as a structural member, but for applications that require fire resistance, it requires relatively expensive fire-resistant coating. Since this is necessary, there is a problem in that construction costs are high. Therefore, the present inventors developed a low yield ratio heat-resistant steel material (hereinafter simply referred to as heat-resistant steel material) with excellent fire resistance suitable for manufacturing shaped steel, and previously filed an application for the same. This heat-resistant steel material has a high yield strength at high temperatures, so there is usually no need for fire-resistant coating, and even if it is necessary, only an extremely thin fire-resistant coating is required, but the price is slightly higher than that of general structural rolled steel materials. There are challenges. An object of the present invention is to provide a method for manufacturing a heat-resistant section steel having excellent fire resistance and economical efficiency by joining steel materials with excellent fire resistance and general steel materials. [Means for Solving the Problems] The gist of the present invention is as follows. (1) In terms of weight ratio, C 0.04 to 0.15%, Si 0.6% or less,
Mn 0.5~1.6%, Nb 0.005~0.04%, Mo 0.4~
A steel billet consisting of 0.7%, Al 0.1% or less, N 0.001 to 0.006%, and the balance Fe and unavoidable impurities.
A method for producing build-up heat-resistant section steel, in which heat-resistant steel material is heated in a temperature range of 1100°C to 1300°C, then subjected to hot plastic working in a temperature range of 800°C to 1000°C, and then air cooled, and then welded and joined to general structural steel material. (2) Weight ratio: Ti 0.005~0.10%, Zr 0.005~
0.03%, V 0.005~0.10%, Ni 0.05~0.5%,
Cu 0.05~1.0%, Cr 0.05~1.0%, B 0.0003
~0.002%, Ca 0.0005~0.005%, REM 0.001
2. The method for producing a build-up heat-resistant section steel according to 1 above, which contains one or more of 0.02% and 0.02%. [Function] The present invention uses well-known hot plastic processing such as rolling, forging, and hot pressing as a raw material, and further processes such as cold working by rolling, bending, cutting, and pressing to form a section steel. Because the steel section is made by welding together heat-resistant steel formed as structural members and general structural steel formed using exactly the same method, the heat-resistant steel is placed on the side with a large thermal load, and the side with a small thermal load is placed on the side. It has a configuration that is oriented toward general structural steel materials, and the fireproof coating can be eliminated or reduced, making it possible to achieve an economical design. In addition, since it can be manufactured in any shape and size, it is possible to adopt the most mechanically advantageous design and reduce construction costs. Next, as a heat-resistant steel material, C 0.04 ~
0.15%, Si 0.6% or less, Mn 0.5-1.6%, Nb
0.005~0.04%, Mo 0.4~0.7%, Al 0.1% or less,
Since we use a low yield ratio steel with excellent fire resistance that contains 0.001 to 0.006% N and the balance is Fe and unavoidable impurities, it is inexpensive, has good workability in welding, etc., and has low thermal and mechanical strength. We can also provide heat-resistant shaped steel with excellent performance. Furthermore, as a heat-resistant steel material, the weight ratio is C 0.04~
0.15%, Si 0.6% or less, Mn 0.5-1.6%, Nb
0.005~0.04%, Mo 0.4~0.7%, Al 0.1% or less,
N 0.001-0.006% plus Ti 0.005-0.10%,
Zr 0.005~0.03%, V 0.005~0.10%, Ni 0.05
~0.5%, Cu 0.05~1.0%, Cr 0.05~1.0%, B
0.0003-0.002%, Ca 0.0005-0.005%, REM
When using a low yield ratio steel with excellent fire resistance that contains one or more of 0.001 to 0.02%, with the remainder consisting of Fe and unavoidable impurities, it also has good workability in terms of welding, etc. In addition, we can supply heat-resistant steel sections that are advantageous in terms of fire resistance. Next, by using one of the following types of general structural steel materials: rolled steel materials for general structures, rolled steel materials for welded structures, weather-resistant hot-rolled steel materials for welded structures, and highly weather-resistant rolled steel materials, quality that meets the standards is achieved. It is possible to produce a heat-resistant section steel that has the following structural members and is also inexpensive. Now, the heat-resistant steel material according to the present invention will be explained in more detail. As is well known, if we take buildings as an example, they have recently become more and more high-rise, and due to improvements in design technology and high reliability, fire-resistant designs have been reviewed.
A new fire-resistant design method for buildings was established in 2017, and instead of being subject to the above-mentioned 350℃ temperature limit, the high-temperature strength of steel and the load actually applied to buildings
It has become possible to determine the capacity of fire-resistant coatings, and in some cases it has become possible to use steel without coatings. However, there is currently no steel material that has excellent fire resistance and can be supplied to the market at an economical price for use in fixed structures. As a result of research on the strength of steel materials in the event of a fire, the present inventors found that when uncoated use is targeted, the maximum temperature reached in the event of a fire is 1000°C, so that the steel material has 70% or more of its room temperature yield strength at that temperature. It was learned that in order to provide a yield strength of 1, a large amount of expensive metal elements must be added, which results in a loss of economic efficiency. In other words, the unit price of the steel material becomes higher than the cost of the well-known steel material and, in addition, the cost of constructing the fireproof coating, and such steel material cannot be practically used. Therefore, as a result of further research, we found that the most economical steel material was one whose high-temperature yield strength at 600°C was 70% or more of that at room temperature, and by reducing the amount of expensive additive elements and thinning the fireproof coating. We have developed a heat-resistant steel material for use in the present invention, that is, a steel material that can be used without coating when the fire load is small. However, the feature of the manufacturing method is that the weight ratio of C
0.04-0.15%, Si 0.6% or less, Mn 0.5-1.6%,
After reheating a steel piece containing 0.005 to 0.04% Nb, 0.4 to 0.7% Mo, 0.1% or less Al, and 0.001 to 0.006% N, with the balance consisting of Fe and unavoidable impurities in a temperature range of 1100°C to 1300°C, Hot plastic working at 800℃~1000℃
Other methods have a weight ratio of C 0.04 to 0.15%, Si 0.6% or less,
Mn 0.5~1.6%, Nb 0.005~0.04%, Mo 0.4~
0.7%, Al 0.1% or less, N 0.001-0.006% plus Ti 0.005-0.10%, Zr 0.005-0.03%, V
0.005~0.10%, Ni 0.05~0.5%, Cu 0.05~1.0%,
Cr 0.05~1.0%, B 0.0003~0.002%, Ca
A steel billet containing one or more of 0.0005 to 0.005% and REM 0.001 to 0.02%, with the balance consisting of Fe and unavoidable impurities, is reheated in a temperature range of 1100°C to 1300°C and then subjected to hot plastic working. It is characterized by finishing in the temperature range of 800℃~1000℃. Now, as mentioned above, the characteristics of the heat-resistant steel used in the present invention are that it contains a trace amount of Nb and a considerable amount of low C-low Mn steel.
The method involves reheating a steel slab with a composite composition containing Mo at a high temperature and then finishing rolling at a relatively high temperature, and the steel and steel materials (hereinafter simply referred to as steel) produced by the above method are It has the characteristics of having appropriate room temperature yield strength and high high temperature yield strength. In other words, the ratio of proof stress in the temperature range of 600℃ to room temperature proof stress is large, and the reason for this is that there are few basic components other than Nb and Mo, and the microstructure is a relatively large ferrite-based structure. In the case of fine-grained ferrite, quenched, and tempered structures, the yield strength at room temperature is higher than the yield strength in the 600°C temperature range, and the temperature specifications cannot be met. The steel according to the present invention has a low yield ratio and excellent earthquake resistance, and this is also because the microstructure is composed of relatively large ferrite. Next, the characteristic constituent elements of the steel of the present invention and their addition amounts will be explained. Nb and Mo form fine carbonitrides, and
Mo increases high-temperature strength through solid solution strengthening, but it is difficult to obtain sufficient yield strength in the high-temperature range of 600°C by adding Mo alone. As a result of research, the present inventors have found that adding Nb and Mo in combination is extremely effective in increasing the yield strength in the high temperature range. However, if the amount of Nb and Mo is too high, weldability will deteriorate,
Furthermore, the toughness of the weld heat affected zone (HAZ) deteriorates, so the upper limit of Nb and Mo content is 0.04% and 0.04%, respectively.
It is necessary to set the content to 0.7%, and the lower limit is 0.005% and 0.4%, respectively, as the minimum amount to obtain a composite effect. Now, at room temperature, it satisfies the performance specified in rolled steel materials for welded structures (JIS G 3106), and
In order to maintain high yield strength at a high temperature of 600℃, the conditions for reheating and rolling the steel as well as the steel components are important. It is necessary to sufficiently dissolve these elements during reheating, and therefore the lower limit of the reheating temperature is set at 1100°C. In addition, if the reheating temperature is too high, the crystal grains will become large and the low temperature toughness will deteriorate, so the upper limit is 1300.
It must be brought to ℃. Furthermore, the reason why the rolling end temperature is set to a high temperature of 800°C or higher is to prevent carbonitrides of Nb and Mo from precipitating during rolling. When these elements precipitate in the γ region, the size of the precipitates becomes large. High-temperature yield strength decreases significantly. The well-known low-temperature rolling (controlled rolling) is an essential condition for steel materials that require low-temperature toughness, such as line pipes.
In cases where there is no high demand for low-temperature toughness, such as in the steel of the present invention, and where the balance between room-temperature strength and high-temperature strength at 600°C is important, rolling must be completed at a high temperature, which is a condition for reducing the yield ratio. It is also important. In addition, in the present invention, the upper limit of the rolling end temperature is
The temperature was set at 1000°C to ensure the toughness of the steel for construction. Now, the use of Mo in order to increase high-temperature strength is known in conventional heat-resistant steel, but steel with a compound addition of a small amount of Mo and a small amount of Nb is known as a heat-resistant steel material used for construction. It has not been done. Of course, axial ferrite steel for line pipes is known as a steel material with a composite addition of Nb and Mo, but in order to achieve its purpose, axial ferrite steel is manufactured by rolling with controlled strength. Since both the room-temperature yield strength and the high-temperature yield strength are high and the ratio is small, the steel material naturally does not meet the standards for construction steel and cannot be used for construction. Furthermore, in addition, the axial ferrite steel has a higher Mn content and a lower Mo content than the steel according to the present invention. This is because, unlike the steel of the present invention, it is important to increase low-temperature toughness, and there are significant differences between the two in terms of purpose and function and effect. Next, the reason for limiting components other than Nb and Mo in the present invention will be explained in detail. C is for ensuring the strength of the base metal and welded part, and Nb,
It is necessary to exhibit the effect of Mo addition,
If it is less than 0.04%, the effect will be weakened, so the lower limit is set at 0.04%. Furthermore, if the amount of C is too large, the weld heat affected zone (hereinafter referred to as
The upper limit is 0.15% because it not only adversely affects the low-temperature toughness of the HAZ but also deteriorates the toughness and weldability of the base metal. Si is an element contained in steel for deoxidation purposes, and as Si increases, weldability and HAZ toughness deteriorate, so the upper limit was set at 0.6%. In the steel of the present invention, Al deoxidation is sufficient, and Ti deoxidation may also be used. About Si HAZ
From the viewpoint of toughness, it is desirable that the content be approximately 0.15%. Next, Mn is an essential element for ensuring strength and toughness, and its lower limit is 0.5%. However, if the amount of Mn is too large, not only will hardenability increase and weldability and HAZ toughness deteriorate, but it will also be impossible to obtain base metal strength that meets the target standards. For this reason, the upper limit of the Mn content was set at 1.6%. Al is an element generally included in deoxidized steel,
Deoxidation is also carried out by Si and Ti, so
In the present invention, there is no lower limit for Al. However, if the amount of Al increases, the cleanliness of the steel will deteriorate and the toughness of the weld will deteriorate, so the upper limit was set at 0.1%. N is generally contained in steel as an unavoidable impurity, but carbonitrides Nb combined with Nb
(CN) and is effective in improving high-temperature strength. For this reason, a minimum amount of 0.001% is required, but since increasing the amount of N promotes deterioration of HAZ toughness and occurrence of surface flaws in continuous casting slabs, the upper limit was set at 0.006%. Note that the steel according to the present invention contains P and S as inevitable impurities. Since P and S have a small effect on high-temperature strength, their amounts are not particularly limited, but generally the properties of steel with respect to toughness, strength in the thickness direction, etc. are improved as the P and S elements are reduced. Desirable amounts of P and S are each 0.02%,
It is 0.005% or less. The basic components of the steel of the present invention are as described above, and the purpose can be fully achieved. However, in order to further improve the characteristics for the purpose, the following elements, namely Ti, Zr,
By selectively adding V, Ni, Cu, Cr, B, Ca, and REM, more favorable results can be obtained in terms of improving strength and toughness. Next, the additive elements and their amounts will be explained. Ti is an element that has almost the same effect as Nb mentioned above, and when the amount of Al is small at 0.005 to 0.02%, Ti
It forms oxides and carbonitrides to improve HAZ toughness, but if it is less than 0.005% it has no effect, and if it exceeds 0.1% it will have an adverse effect on weldability etc., which is not desirable. V is also an element that has almost the same effect as Nb and Ti, and although its effect on high-temperature yield strength is smaller than that of Nb and Ti, it improves HAZ toughness in the range of 0.005 to 0.10%. However, if it is less than 0.005%, it has no effect, and if it exceeds 0.10%, it has an unfavorable effect on HAZ toughness. Next, Ni improves the strength and toughness of the base metal without adversely affecting weldability and HAZ toughness, but if it is less than 0.05%, the effect is weak, and if it is added more than 0.5%, it is not suitable for the purpose of building steel. Since it becomes extremely expensive and loses economic efficiency, the upper limit was set at 0.5%. Cu has almost the same effect as Ni, and also has the effect of increasing high-temperature strength and improving corrosion resistance due to Cu precipitates. However, if the Cu content exceeds 1.0%, the
The amount of Cu is limited to 0.05 to 1.0% because Cu cracks occur, making manufacturing difficult, and there is no effect if it is less than 0.05%. Cr is an element that increases the strength of the base metal and weld zone, but if it exceeds 1.0%, it deteriorates weldability and HAZ toughness, and if it is less than 0.05%, it has little effect. Accordingly
The amount of Cr is 0.05 to 1.0%. According to the knowledge of the present inventors, Cr is an element that increases high temperature strength like Mo, but unlike Mo, the effect of increasing high temperature strength at 600°C is small compared to the increase in room temperature strength. B is an element that increases the hardenability and strength of steel, and BN combined with N acts as a ferrite generation nucleus and refines the HAZ structure. In order to obtain this effect of B, a minimum amount of B of 0.0003% is required; anything less than that has no effect, and B
If the amount is too large, coarse B-constituents will precipitate at the grain boundaries of the HAZ, deteriorating the low-temperature toughness. Therefore, the upper limit of the amount of B is limited to 0.002%. Ca, REM controls the morphology of oxide (MnS),
In addition to increasing Shapey absorption energy and improving low-temperature toughness, it is also effective in improving hydrogen organic cracking resistance. However, if the amount of Ca is less than 0.0005%, it has no practical effect, and if it exceeds 0.005%, CaO,
A large amount of CaS is generated and becomes large inclusions that impair not only the toughness but also the cleanliness of the steel, and also have a negative effect on weldability.
It shall be 0.005%. Further, REM has the same effect as Ca, and if the amount added is increased, the same problems as Ca occur, and the economy is also poor, so the lower limit of the amount of REM is set to 0.001% and the upper limit is set to 0.02%. In addition, after manufacturing the steel of the present invention, it is used for purposes such as dehydrogenation.
Even if the steel is reheated to a temperature below the Ac ₁ transformation point, the characteristics of the steel of the present invention are not impaired in any way. In addition, in the present invention, as described above, the steel slab is reheated and then subjected to hot plastic working to produce a product.
The product may be further subjected to hot plastic working. For example, in addition to forming a bloom or billet into a shape steel, the product may be used as a raw material and cold-worked to produce a desired steel material such as a shape steel or a steel pipe. At that time, heat treatment is appropriately performed as necessary. [Example] Steel plates (thickness 20 to 50 mm) with various steel compositions were manufactured using well-known converter, continuous casting, and plate processes.
We investigated high-temperature strength, etc. Tables 1, 2, and 3 show a comparison of the components of the steel of the present invention and comparative steel, and Tables 4 to 8 show the mechanical properties according to heating, rolling, and cooling conditions. As is clear from Tables 4 to 8, all the steels according to the present invention have good strength at room temperature and high temperature, whereas all the comparative steels have too high strength at room temperature or have poor high temperature strength. In addition, the ratio of strength at 600℃ to room temperature strength is low.
Not suitable as a fireproof construction material.

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[Table] Next, in order to facilitate understanding of the mechanical properties of the steel of the present invention, the mechanical properties will be explained using graphs in comparison with well-known steel materials. Table 9 shows a compositional comparison between the steel of the present invention and JIS G 3106 rolled steel for welded structures (SM50A), and FIG. 10 is a graph comparing the fire resistance of both.

[Table] In Figure 10, the YP ratio is plotted on the vertical axis and the temperature (°C) is plotted on the horizontal axis.
A broken line 52 shows the change in SS41, and a broken line 53 shows the change in SM50A. As is clear from Fig. 10, the difference disappears at temperatures exceeding 800°C, but the steel of the present invention
It maintains twice the proof strength of SM50A at ℃,
It can be seen that it has excellent properties as a building steel material. From this, it is clear that compared to SM50A and S41, the steel of the present invention requires a thinner fire-resistant coating when the fire load is the same, and when the fire load is not large, it is possible to get away with no coating. it is obvious. Now, as a result of conducting various experiments on the above-mentioned heat-resistant steel materials, such as applying fire-resistant coatings and applying heat-resistant paints, we found that the amount used in both cases was extremely small compared to well-known steel materials for the same fire load. It was confirmed that it can be done without coating, or that it has sufficient strength even without coating. Therefore, the inventors of the present invention have found that by using the heat-resistant steel material for some of the structural members of built-up sections, they can meet design requirements with a wide dimensional tolerance and flexibility, without having the dimensional limitations of rolled sections. The heat-resistant steel material of the present invention has been developed, which is not only capable of oxidation, but also has excellent fire resistance and is highly economical, and will be described in detail below with reference to Examples. 1A to 1F are schematic cross-sectional views of embodiments of the bulldoped heat-resistant steel section according to the present invention, (a) is a cross-sectional view of the section steel 1, the flange 2 is made of heat-resistant steel, the flange 3a, and the web 3b. is JIS G
Constructed from general structural rolled steel according to 3101. (b) is a cross-sectional view of the channel steel 4, the flange 5 is made of heat-resistant steel, the flange 6a and the web 6b are made of JIS G 3106.
It is constructed from rolled steel for welded structures. (c) is a cross-sectional view of the angle iron 7, in which the flange 8 is made of heat-resistant steel, and the flange 9 is made of weather-resistant hot-rolled steel JIS G 3114 for welded structures. (d) is a cross-sectional view of the square steel pipe 10, where the channel steel 11 is made of heat-resistant steel and the channel steel 12 is made of highly weather-resistant rolled steel JIS G
Consists of 3125. (e) is a cross-sectional view of the column 13, where the lip channel steel 14 is heat-resistant steel and the lip channel steel 15 is a general structural steel.
It is composed of JIS G 3101. (f) is a cross-sectional view of the section steel 16, in which the flange 17a and web 17b are made of heat-resistant steel, and the flange 18 is made of general structural steel material JIS G 3101. Now, FIG. 2 is a partial sectional view of an embodiment in which the H-shaped steel 16 is used as a beam to support a concrete slab 19, and shows a flange 17a, a web 17
If b is made of heat-resistant steel and the fire load is small,
Since there is no need to apply a fireproof coating, the fireproof insulation layer 20
The thickness T ₂ is sufficient as a protective thickness to cover the flange 18 as shown by the broken line 21 indicating the surface of the fireproof insulation layer 20, and even when the fire load is large,
The thickness of the fireproof insulation layer can be less than half that of the conventional one. For conventional H-beam steel, the thickness is surrounded by the dashed line 22.
Although _T2 fire-resistant coating was necessary, the amount of fire-resistant coating that can be saved with the heat-resistant section steel of the present invention is the above-mentioned difference, so the cost savings are significant. Next, in Fig. 3, the outer wall concrete 2 is attached to the pillar material 23.
4 is a schematic cross-sectional view of an embodiment in which 25
26 indicates an interior board, and 26 indicates an instruction beam. The pillar material 2
3 is a lip channel steel 27 made of heat-resistant steel and a lip channel steel 28 made of general structural steel JIS G 3101.
It consists of Conventionally, the thickness of the fireproof coating indicated by the dashed line 29 is required, but the exposed surface 27a of the pillar material 23 is
Since is made of heat-resistant steel, the maximum thickness of the fireproof covering 30 is the same as that of the exposed surface 27a, as shown by the symbol T ₃ , and even when the fire load is large, the maximum thickness is the same as that of the exposed surface 27a, as shown by the symbol T ₄ .
As shown in Figure 2, since a slightly thicker fireproof coating layer is sufficient, the amount of savings in fireproof coating material is considerable. Next, in FIG. 4, only the lower flange 31 supports the floor slab 33 using H-shaped steel 32 made of heat-resistant steel,
This is a partial cross-sectional view showing concrete filler 34 filled between the flanges of the H-beam 32. Conventionally, it was necessary to wrap the entire H-beam thickly with concrete, but in the present invention, this is simplified as shown in the figure. becomes possible. Figure 5 shows an example in which H-shaped steel is used as a pillar material for a building, and only the inner flange 35 is made of heat-resistant steel.
This is a partial cross-sectional view showing an external wall material 37 supported using a shaped steel 36. The space between both flanges is filled with concrete or a fibrous heat-resistant material 38 in the same way as in FIG. There is no need to encase the steel 36 in thick fibrous heat-resistant material or concrete. Similarly, FIG. 6 shows an example in which H-shaped steel is used as a pillar material for a building, and a partial cross-section is shown in which only the inner flange 39 supports a block wall material 41 using H-shaped steel 40 made of heat-resistant steel. In the figure, concrete or a fibrous heat-resistant material 42 is filled between the block wall material 41 and the inner flange 39. Conventionally, the inner flange 39 was covered with thick concrete, but with the present invention, it is possible to create a simple fireproof structure as shown in the figure. Of course, even in this example, if the fire load is large,
It goes without saying that the inner flange 39 should be coated with a fireproof coating so as not to be exposed, but in that case as well, the thickness may be made much thinner than the conventional one, for example, half the thickness. Next, Figure 7 a and b show general structural steel JIS G
This is a schematic cross-sectional view of an H-beam 43 made of 3101 and an H-beam 44 made of heat-resistant steel, each of which is cut into a sawtooth shape, and the half-cut bodies 43a and 44a are welded together 45a as shown in FIG. ,45b
However, by forming the honeycomb web shaped steel 46, a useful beam material with excellent yield strength can be obtained. Unlike conventional honeycomb web shaped steel 46, the lower side is made of heat resistant steel, so the fireproof coating can be reduced or eliminated as described above, and the through holes 47, 48, 49 can be used for piping. It is expensive, so it can increase the space volume as a structural material for high-rise buildings, and it can reduce equipment costs for the various types of piping, so it can be used in a wide range of areas as an economically efficient member. FIG. 9 shows the honeycomb web shaped steel 46 in the fourth
When filling concrete 50 in an example used as a beam material as shown in the figure, since the through holes 47, 48, and 49 are present, the concrete filling work can be carried out very efficiently. I can do it. In this case, the fireproof coating on the honeycomb web shaped steel 46 can be reduced or eliminated as described above, so the economic effect is great. [Effects of the Invention] The built-up heat-resistant section steel of the present invention can significantly reduce the cost of fireproof coating, has excellent weldability, and has a large degree of freedom in designing desired dimensions, making it extremely useful as an economical structural member. be.

[Brief explanation of drawings]

1a to 1f are schematic sectional views of a build-up heat-resistant section according to the present invention, FIGS. 2 to 6 are schematic sectional views of an embodiment of a build-up heat-resistant section according to the present invention, and FIGS. 7 a and b are FIG. 8 is a schematic side view of a honeycomb web heat-resistant steel section; FIG. 9 is a schematic cross-sectional view of an embodiment of the honeycomb web heat-resistant section steel according to the present invention; FIG. 10 is a schematic cross-sectional view of the honeycomb web heat-resistant section steel according to the present invention. It is a comparison graph of proof stress ratio of heat-resistant steel and comparison steel. 1... Shape steel, 2... Flange, 3a... Flange, 3b... Web, 4... Channel steel, 5... Flange, 6a... Flange, 6b... Web, 7
... angle iron, 8 ... flange, 9 ... flange,
10... Square steel pipe, 11... Channel steel, 12... Channel steel, 13... Pillar material, 14... Lip channel steel, 15
...Rip channel steel, 16...H section steel, 17a...
Flange, 17b...Web, 18...Flange, 19...Concrete floor slab, 20...Fireproof insulation layer, 21...Dotted line, 22...Dotted chain line, 23...
...Column material, 24...Exterior wall concrete, 25...Interior board, 26...Support beam, 27...Rip channel steel, 28...Rip channel steel, 29...Dotted chain line,
30...Fireproof covering material, 31...Lower flange, 3
2... H-beam steel, 33... Floor slab, 34... Concrete filler, 35... Inner flange, 36... H
Shaped steel, 37... Exterior wall material, 38... Fibrous heat-resistant material,
39...Inner flange, 40...H-shaped steel, 41...
...Block wall material, 42...Fibrous heat-resistant material, 43...
...H-shaped steel, 43a...H-shaped steel half-cut material, 44...H
Shaped steel, 44b... H-shaped steel half-cut material, 45a... Welded, 45b... Welded, 46... Honeycomb web shaped steel, 47... Through hole, 48... Through hole, 49...
Through hole, 50... concrete, 51... broken line,
52... broken line, 53... broken line.

Claims (1)

[Claims] 1. C 0.04-0.15%, Si 0.6% or less, Mn 0.5-1.6%, Nb 0.005-0.04%, Mo 0.4-0.7%, Al 0.1% or less, N 0.001-0.006% balance is a steel billet consisting of Fe and unavoidable impurities.
Hot plastic working after heating in the temperature range of 1100℃~1300℃
A method for manufacturing build-up heat-resistant steel sections, in which heat-resistant steel materials that have been air-cooled after being heated in a temperature range of 800℃ to 1000℃ are welded to general structural steel materials. 2. Ti 0.005-0.10%, Zr 0.005-0.03%, V 0.005-0.10%, Ni 0.05-0.5%, Cu 0.05-1.0%, Cr 0.05-1.0%, B 0.0003-0.002%, Ca 0.0005-0.005 %, REM
The method for producing a build-up heat-resistant section steel according to claim 1, which contains one or more of 0.001 to 0.02%.