JPH0559190B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is aimed at preventing the collapse of high-alumina monolithic refractories mainly used for high-temperature applications in steel manufacturing.
This invention relates to a metal fiber made of alloy steel that is used by being embedded in the refractory. [Problems with conventional technology] The materials of metal fibers conventionally used to prevent the collapse of monolithic refractories are mild steel for medium temperature applications, various types of stainless steel for high temperature applications, and 25Cr-20Ni heat-resistant steel for ultra-high temperature applications. The material was Products manufactured from these materials exhibit sufficient heat resistance in medium temperature ranges such as forging or rolling heating furnaces, and high temperature ranges such as homogenization heating furnaces for steel ingots and slabs. However, ultraviolet rays such as tandates and their lids for continuous casting, which come into contact with molten steel for long periods of time, receive radiant heat from molten steel at close range, or receive high-temperature radiant heat during molten steel refining, and immersion tubes used for degassing refining. For high-temperature applications, it lacks oxidation resistance, even compared to the conventional alloy steels mentioned above, and its lifespan is limited to about 40 tappings. For this reason, there has been a demand for a material with even better oxidation resistance and lower material costs. Furthermore, conventional metal fibers do not have sufficient bond strength with high-alumina monolithic refractories for high-temperature applications, which hastened their collapse. [Means for Achieving the Object] Therefore, the present invention aims to provide a metal fiber for reinforcing refractories that can meet the above requirements. To achieve that purpose, the present invention uses chromium.
For reinforcement, a wire rod is formed from alloy steel containing 10 to 27% aluminum, 1 to 7% aluminum, and the remainder iron and unavoidable impurities, and the wire is bent into a wave shape and cut to size. The present invention aims to provide a metal fiber for reinforcing refractories that can be embedded in high alumina monolithic refractories. The present invention also uses chromium to achieve the same purpose.
Contains 10-27% aluminum, 1-7% aluminum, and 0.1-0.6% titanium, 0.01-0.5% niobium, and boron.
Forming a wire rod using alloy steel containing one or more of 0.002 to 0.015% and 0.005 to 0.1% of rare earth elements, with the remainder consisting of iron and unavoidable impurities, and bending the wire into a wave shape. The object of the present invention is to provide a metal fiber for reinforcing a refractory that can be cut into a fixed size and embedded in a high alumina monolithic refractory. [Example] The alloy steel of this example contains 16% chromium, 2% aluminum, and the remainder consists of iron and unavoidable impurities. This unavoidable impurity is carbon
0.15% or less, silicon 0.01~2.0%, manganese 0.01~
1.5%, Nickel 0.02% to 2.0%, etc. In this alloy steel, the chromium content must be in the range of 10 to 27%, since the oxidation resistance is improved when the chromium content exceeds 27%, and the cold workability becomes extremely poor. Furthermore, by adding aluminum to this, oxidation resistance is significantly improved. This is because an aluminum oxide film is deposited on the surface of the alloy.
This is thought to be due to protecting the base metal from oxidation. At the same time, this aluminum oxide coating is combined with alumina contained in refractories for high-temperature applications at high temperatures, and as a result, the metal fibers are chemically bonded with alumina through the aluminum oxide coating. Therefore, even if a crack occurs in the refractory, the fibers will not easily come out, which is thought to prevent the refractory from collapsing. Such an effect can be seen from an aluminum content of 1%, and it is usually sufficient to include 2% or more, but if it exceeds 7%, it is not only uneconomical because the cost of raw materials increases, but also reduces the amount of aluminum oxide generated. The aluminum content should be in the range of 1 to 7%, since the aluminum content would be excessively high and the hard coating would cause significant roll wear during rolling. In addition, this alloy steel contains 0.1 to 0.6% titanium and niobium.
By adding one or more of 0.01 to 0.5%, boron 0.002 to 0.015%, and other rare earth elements 0.005 to 0.1%, the grain size of this alloy steel can be adjusted and workability can be improved. . However, these additive components have no effect below the above lower limit, and if they exceed the upper limit, they not only worsen workability but also interfere with precipitation of aluminum oxide, so the above additive components must be within the above range. . However, in order to form a metal fiber using the alloy steel of the lever, the alloy steel is first rolled into a wire or strip shape, and then subjected to mild cold working to increase its strength at room temperature. The metal fiber for reinforcing refractories of the present invention is obtained by bending this wire into a wave shape and cutting it into a fixed size. Table 1 shows the results of a sublimeness comparison test between the corrugated metal fiber according to the present invention shown in FIGS. 4 to 7 and the straight bar-shaped metal fiber shown in FIGS. 1 to 3. Ta. In other words, it can be made into a shaft with a round cross-section as shown in Figure 1, or a belt-shaped material can be cut into a shaft with an angular cross-section as shown in Figure 2. As shown in Fig. 3, the wire rod is formed into a shape with a constant pitch and variable shaft diameter, while the wire is formed into a waveform with a constant pitch and width as shown in Fig. 4, or a waveform with a constant width as shown in Fig. 5. It can be bent into a rectangular waveform such as the one shown in FIG. Various forms of metal fibers are formed by this process. Table 1 shows the average top surface of the metal fibers and the bottom surface of the container after a large number (200 g) of the metal fibers in the form shown in FIGS. This figure shows the results of measuring the height from . In this way, the wavy or rectangular wavy metal fibers shown in Figures 4 to 7 have more than five times the sublime quality than the straight rod-shaped metal fibers shown in Figures 1 to 3. One thing was confirmed. From this, it can be seen that the waveform shape is highly intertwined and tends to be bulky, and it can be said that making the waveform have unequal pitch and/or width can further improve the bulkiness.

[Table] The metal fibers formed in this way are kneaded into high alumina monolithic refractories and constructed into required refractories such as furnace walls. At that time, the metal fibers form a three-dimensional network in the refractories. The refractories are buried in an entangled state, and the intertwined structure increases the mechanical strength of the refractory. In addition, the cross-sectional shape of the wire may be not only circular but also oval, rectangular, etc. In that case, the wire diameter in order to improve economic efficiency is a short axis or thickness of 0.1 to 1 mm, a major axis or width of 0.2 to 2 mm, and a length of 10 to 1 mm. A waveform of 80 mm and a waveform pitch of 2 to 6 mm were practically effective. In addition, when cutting the wire rod, it causes burrs, burrs, slight bends and twists, and by creating a shape that is a combination of these, the mechanical bond with the refractory becomes stronger, making it fireproof. This has the effect of making it difficult for the fiber to come out even if a crack occurs in the object. When the metal fibers produced in this way were mixed into high-alumina monolithic refractories and used as converter tundishes, the lifespan was approximately 1.5 times longer than that of conventional materials. That is, the life of the conventional converter tundish was about 40 times, but when the metal fiber of the present invention was mixed in, the life was extended to 60 times. Table 2 shows the chemical composition of conventionally used mild steels, various chromium steels, various stainless steels, and the alloy steel of the present invention, and after embedding them in high alumina monolithic refractories and heating them at 1250°C for 200 hours. showed the oxidation depth of Generally, the bond strength between a refractory and a metal depends on the strength of the metal oxide coating and the boundary strength between the coating and the refractory. If the metal oxide film is thick,

【table】

〔Effect of the invention〕

As explained above with respect to the embodiments, the metal fiber for reinforcing refractories of the present invention significantly improves oxidation resistance by containing predetermined amounts of chromium and aluminum. By embedding the metal fiber in the metal fiber, the alumina is chemically and firmly bonded to the thin and strong aluminum oxide film precipitated from the metal fiber. Therefore, due to the combined effect of its strong bond and oxidation resistance, separation from the refractory is suppressed and the structure can be strongly reinforced. In addition, since the metal fibers are formed by bending wire rods into a wave shape, the metal fibers intertwine with each other in a three-dimensional net shape in the refractory material, which has the effect of increasing its mechanical strength and further improving its durability. .

[Brief explanation of the drawing]

1 to 3 are perspective views of straight bar-shaped metal fibers, and FIGS. 4 to 7 are perspective views of corrugated metal fibers showing embodiments of the present invention.

Claims (1)

[Claims] 1 10 to 27% chromium, 1 to 7% aluminum
A wire rod is formed from alloy steel with the remainder being iron and unavoidable impurities, and the wire rod is bent into a wave shape and cut to a specified size.The wire rod is embedded in a high alumina monolithic refractory for reinforcement. Metal fiber for reinforcing refractories. 2 Chromium 10-27%, aluminum 1-7%
Contains 0.1-0.6% titanium and 0.01-0.5 niobium
%, boron 0.002~0.015%, rare earth elements 0.005~
High alumina made by forming a wire rod from alloy steel containing one or more of 0.1% and the rest consisting of iron and unavoidable impurities, bending the wire into a wave shape and cutting it to a fixed size. Metal fiber for reinforcing refractories to be embedded in monolithic refractories.