JPH039018Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to an improvement of a sample collection tube for quantifying hydrogen in molten metal. (Prior Art) In steelmaking and aluminum smelting, it is important to reduce the amount of hydrogen in molten metal as much as possible in order to improve the mechanical properties of the final product. Conventionally, to quantify hydrogen in molten metal (hereinafter referred to as molten metal), the molten metal is sucked up in a quartz tube, rapidly cooled with water, cut to a specified size, polished, and then melted in an inert gas. - Gas chromatography - It is generally quantified by thermal conductivity detection method. However, in the above-mentioned sampling-quantification method,
When the molten metal solidifies, the solubility of hydrogen drastically decreases, and a large amount of hydrogen is released. However, this released hydrogen escapes into the atmosphere and cannot be quantified, and after solidification, the sample is in a supersaturated state at room temperature. cutting,
It is difficult to accurately quantify hydrogen in the molten metal because hydrogen escapes during analysis preparation work such as polishing. Several proposals have been made to solve these difficulties. The first method involves sucking up the molten metal into a vacuum quartz tube filled with thin-walled cylindrical stainless steel, allowing the hydrogen released during solidification to be absorbed into the stainless steel, which has a high hydrogen solubility, and cutting the sample along with the stainless steel cylinder. (Narita et al., Tetsu-to-Hagane, 65 , 1979, 1620). However, when this method is used, a fine gap is created at the boundary between the solidified metal and the stainless steel cylinder, and water that enters the gap during water cooling can decompose and generate hydrogen when melted for analysis, causing errors. In addition, the stainless steel cylinder that is inserted must be completely dehydrogenated beforehand, otherwise there will be large errors. The second is that, as shown in FIG. 5, the hollow body is composed of a thin metal wall 12 and a cover cap 13, and the joint part of the outer wall of the hollow body containing the sample mold 14 is vacuum-evacuated using only metal materials. (Japanese Patent Publication No. 53-45157). The cover cap _3-1 of this collection tube is immersed in the molten metal, the molten metal is sucked into the internal mold 14, and then cooled to release the hydrogen in the molten metal into the vacuum chamber 15 and collect it. As shown, one end (the other end of the cover cap immersed in the molten metal) is inserted into a container 17 connected to a gas analyzer 16 to seal the inlet, and then a hole is made in the outer wall 12 to collect the hydrogen collected in the vacuum chamber 15. It is used to quantify. (Here, when the entire collection tube is placed in a sealed container and the wall 12 is perforated, not only the hydrogen released into the vacuum chamber 15 from the molten metal sucked into the mold 14 but also part of the hydrogen released from the steel of the suction base 18) ) This method prevents the escape of hydrogen released during sample solidification, and also eliminates the need for cutting and polishing the sample. Errors are also prevented. However, this proposal still has some drawbacks. (a) Walls made of thin metal when immersed in molten metal 1
In order to prevent 1 from being eroded and damaged, the sampling tube is covered with a heat insulating material, but since part of this heat insulating material contains an organic binder, it burns and the molten metal boils, causing air to escape. The entrainment occurs, and part of the heat insulating material melts to form slag, increasing the amount of C, H, O, Si and inclusions in the molten metal. In the tundish or mold of a continuous casting machine immediately before slab casting, this adverse effect exceeds the permissible limit, so its use is limited to the previous process. (b) Even if the heat insulating material is removed and the outer wall 11 is immersed in molten steel for a short time to suck up the molten metal to prevent melting damage, the molten metal will adhere to the outer periphery of the outer wall 12 and cover cap 13 and solidify. That is inevitable. If metal adheres to the outer periphery, it becomes very difficult to put one end of the sampling tube into the container 17 as explained in FIG. 6 and seal the gap between the container 17 and the sampling tube, making hydrogen determination virtually impossible. It becomes possible. (c) A rubber O-ring is usually used to seal between the container 17 and the sampling tube, but to prevent it from burning out, the sampling tube is cooled with water after sucking up the molten metal. In the case of steel, about 5 to 10% of the total hydrogen remains in the steel sucked into the mold, so after quantifying the hydrogen in the vacuum chamber 15, a part of the mold 14 containing the steel is cut. Then, it is necessary to separately quantify the residual hydrogen using a heated extracted hydrogen quantitative device and add it up. This operation poses a significant difficulty in obtaining analytical results quickly. In order to solve the above-mentioned difficulties, the present inventor has already proposed a method in which the vessel wall is made of an inorganic refractory, and one end has a molten metal suction port that is eroded and opened when the sample is immersed in the molten metal. made of a hydrogen-permeable material so as to form a cavity in which the molten metal sucked up solidifies into a predetermined shape by communicating with the suction port in a tubular body having a vacuum inside. A sample collection tube for quantifying the amount of hydrogen in molten metal, which has a built-in conduit and a space for accommodating the hydrogen released during solidification and cooling of the molten metal (Utility Application 1983-
No. 141889 (Utility Model Publication No. 59-47869)) was proposed. According to this sample collection tube (the conceptual diagram is shown in Figure 7), the sample collection tube mentioned earlier (Special Publication No. 53-45157)
difficulties have been resolved. Namely, (a) the use of inorganic refractories such as quartz or alumina in place of thin metal walls and cover caps greatly improves heat resistance when immersed in molten metal (this is simply due to the (It is greatly influenced not only by the difference but also by the difference in thermal conductivity.) As a result, it is no longer necessary to cover the pipe with a heat insulating material, which is essential for known sampling pipes, and contamination of the molten metal by the heat insulating material is prevented, allowing use in tundishes and continuous casting molds. (b) According to this collection tube, the collection tube is located at the suction base 1.
8, the above-mentioned error due to the suction base can be prevented, and it is therefore possible to completely insert the entire collection tube into the collection container (FIG. 8) for quantitative determination. Furthermore, as a result, it is no longer necessary to use an O-ring to seal the collection container, and a high-temperature metal packing can be used to seal the collection container 19 and the lid 20. It can be directly inserted into the collection container 19 without water cooling. By omitting the water cooling operation, the rate of hydrogen gas released from the metal inside the conduit (mold) into the hollow space increases significantly (from about 90% to about 98%), and the amount of hydrogen remaining in the solidified metal decreases. This decreases to an almost negligible level, and its variation is also extremely reduced. Therefore, it becomes possible to omit quantitative determination of residual hydrogen, which greatly contributes to shortening analysis time. (c) Known sample tubes with large volume suction bases (Japanese Patent Publication No. 53-45157) usually have a tube inside the suction base in order to control the solidification rate of the molten metal at the suction base to an appropriate value. A chiller has been inserted. Insertion of this cooling metal causes new trouble. That is, for example, when the molten steel temperature drops to about 1500° C., the sucked up molten steel solidifies at the suction base without reaching the mold, and sampling of the molten steel often ends in failure due to poor suction. On the other hand, according to this sample collection tube, there is no need for a cooling metal to be inserted into the inside of the suction base, so even molten steel at approximately 1500°C can be suctioned without any problems. (Problems that the invention attempts to solve) According to recent detailed experiments by the inventor of the present invention, there are still some problems remaining with the method of Utility Application No. 141,889/1989 (Patent Application No. 47,869/1983). It became clear that this was the case. That is, after sucking up the molten steel in the sampling pipe (Fig. 7), before placing it in the sampling container (Fig. 8) and breaking the sampling pipe, and quantifying the hydrogen in the residual space 7, the collection is carried out. It is sometimes observed that some of the hydrogen produced escapes. In particular, when a metal conduit (mold part 3) is used in the vessel wall 1 made of inorganic refractories, when escape occurs, a temper color is generated on the outer surface of the metal conduit 3 due to oxidation, and the vessel wall Since no cracks were observed in 1,
This is due to the difference in the coefficient of thermal expansion between the inorganic refractory wall 1 and the metal conduit 3, when the metal conduit that has thermally expanded as the molten steel is sucked up is gradually cooled down. It is considered that air enters the interior through the interface between the vessel wall 1 and the conduit 3 at the open end of the suction section 2, and at the same time hydrogen diffuses to the exterior. Therefore, in order to prevent gas movement from the interface between the vessel wall 1 and the conduit 3 at the opening of the suction part 2 after suction, the collection tube is capable of sealing the interface after suction. was developed. (Means for solving the problem) The present invention effectively solves the above-mentioned problems, and its gist is that the vessel wall is made of an inorganic refractory, and one end is attached to the molten metal of the sample. The tubular body has a molten metal suction port which is opened by melting when immersed in the tubular body and has a vacuum inside. Quantifying the amount of hydrogen in a molten metal containing a conduit made of a hydrogen-permeable material so as to form a cavity for solidification, and a space for accommodating hydrogen released during solidification and cooling of the molten metal. (a) forming a protrusion on the outer periphery near the suction port of the conduit, (b) inserting a low-melting point substance into the space between the conduit and the vessel wall, (c) reducing the suction of the conduit. A cylindrical opening inner tube connected to the vessel wall is provided inside the end on the upper mouth side, (d) A metal thin plate or wire is wrapped around the outer circumference of the vessel wall near the suction opening, (a) above. , (b), (c), and (d) either singly or in combination. The content of the present invention will be explained in detail below based on the drawings. Figures 1, 2, 3, and 4 each show an example of an embodiment of the sample collection tube of the present invention. When the suction port 2, which is a thin part of the wall 1 of the collection pipe made of material, is immersed in molten metal, this part will be eroded and the molten metal will be sucked into the pipe 3 made of a thin steel plate that has been previously dehydrogenated. The water reaches the cold metal 4 which has been dehydrogenated in advance, closes the vent hole 5, and solidifies. 6 is a fixing member for fixing the conduit 3 at a certain position within the collection tube. Hydrogen released due to reduction in hydrogen solubility due to solidification and cooling diffuses through the vent 5 or through the conduit 3 at right angles to the longitudinal direction and is collected in the residual space 7. In FIG. 1, near the suction port 2 of the conduit 3,
After a metal ring 8 is joined or fitted in advance, it is covered with an inorganic refractory material to form the wall 1 of the collection tube. In addition, a metal flange may be joined near the suction port 2 of the conduit 3 and the outside thereof may be covered with an inorganic refractory material to form the wall 1 of the sampling pipe. Expanding a portion of the conduit 3 in the length direction, changing the diameter of the conduit 3, or bending the conduit 3 is also a means for producing the same effect as shown in FIG. 1. In Figure 2,
A low melting point substance 9 such as soda glass, solder, or solder alloy (adhesive alloy of quartz and iron) is inserted into the space between the conduit 3 and the vessel wall 1 made of inorganic refractory material. In addition, there is also a method in which the outer periphery of the conduit 3 near the suction port 2 is coated with these low-melting-point substances in advance and then covered with an inorganic refractory material to form the collection tube wall 1, as shown in Figure 2. It is a means to bring about the same effect. In FIG. 3, a cylindrical open inner tube 10 is provided inside the suction port side end of the conduit 3 and is connected to the vessel wall. In FIG. 4, a ring is formed by wrapping a metal thin plate or wire 11 around the outer periphery of a container wall 1 which is narrowed to fit with a conduit 3 near the suction port 2. (Function) In the case of Fig. 1, by increasing the boundary area between the conduit 3 and the vessel wall 1, the formation of gaps due to thermal stress is eliminated, and by slowing down the dissipation rate of the captured hydrogen gas, Reduces hydrogen dissipation during the typical sample collection to analysis time. Second
In the case shown in the figure, the inserted low melting point substance exists in a liquid state down to a relatively low temperature when the molten steel is left to cool after being extracted, and fills the gap in the boundary layer between the metal conduit 3 and the constriction part of the vessel wall 1. , to prevent the trapped hydrogen gas from dissipating. In the case of FIG. 3, the molten steel within the conduit 3 and around the outer circumference of the open inner tube 10 strongly compresses the outer circumferential wall of the inner tube when it contracts during solidification, preventing hydrogen gas from escaping from this interface. Ru. In the case of Fig. 4, the molten steel adheres to the metal ring wrapped around the outer circumference of the vessel wall 1 which is squeezed so as to fit with the conduit 3 near the suction part 2, and the molten steel in the conduit 3 is mixed with the molten steel. It connects and solidifies to reduce the gap in the boundary layer between the conduit 3 and the vessel wall 1 during cooling, thereby preventing the trapped hydrogen gas from dissipating. If a large amount of molten steel adheres, it will interfere with the results, so it is important to use thin steel plates or thin steel wires to prevent this. Note that it is also possible to use some or all of the means illustrated in Figures 1 to 4 in combination, which further prevents the possibility of dissipation of collected hydrogen and provides more accurate values with a higher probability. Needless to say, what you can get from it. In addition, in order to complement the present invention and completely prevent the dissipation of hydrogen gas, the area around the suction port of the sampling tube is immersed in a molten pool of low-melting point metals such as lead and solder immediately after sampling the molten metal. It is also effective to cover the surface with water. Examples of the present invention are shown below. (Example) The collection tube of the present invention shown in Fig. 1 (made of quartz with an outer diameter of
12mm, inner diameter 10mm, length 150mm, made of cold-rolled thin steel plate with dehydrogenated inside, plate thickness 0.3mm, diameter 6mm, length 70mm, with a steel wire ring about 1mm in diameter on the outer periphery 5mm from the suction end. Enclose the soldered conduit
10 ^-2 Torr), the collection tube of the present invention shown in Figure 2 (same configuration as above except for the ring, with a gap of about 0.5
g), the collection tube of the present invention shown in Figure 3 (a quartz inner tube with a length of about 5 mm is welded to the wall of the quartz vessel, and a thin steel conduit is attached to the suction tube). (the mouth end is fixed), and the collection tube of the present invention shown in Figure 4 (excluding the ring, the above-mentioned
With the same configuration as the one shown in the figure, a cold-rolled steel plate with a width of 5 mm and a thickness of 0.3 mm was wrapped around the end of the suction port side of the sampling tube in two layers. These collection tubes of the present invention and the Utility Application for Comparison
Using the sampling tube shown in Figure 7 described in No. 141889, 20 samples were each sampled at approximately the same time from molten steel having a composition equivalent to JIS SM50 in a continuous casting mold. After each sample was allowed to cool for 10 minutes, it was placed in 20 stainless steel collection containers 29 (same configuration as shown in Figure 8), and as shown in Figure 9, it was placed in a gas chromatograph - thermal conduction detection type gas. Each collection container 29 is connected to the analyzer 25.
After replacing the inside with Ar gas, the quartz sampling tube was broken with the valve 26 closed. Next, by opening and closing the valve 26 and the three-way valve 27, hydrogen in the collection container was transported to a gas chromatograph by an Ar carrier and quantified by thermal conductivity detection. After completing hydrogen determination,
The sample was taken out and weighed, and the weight of the chiller part and conduit part, which were not involved in the measurement, was subtracted to obtain the sample weight.
The hydrogen content in molten steel was calculated from the released hydrogen amount and the sample weight. The reason why we decided to leave the sample to cool for 10 minutes instead of the usual method of quantifying it immediately after collection (within 2 minutes) was because it took some time to handle a large amount of sample, and also because it clearly demonstrated the effectiveness of this invention in preventing hydrogen leakage. In order to prevent leakage, the cooling time during which leakage could occur was extended. The measurement results are shown in Table 1.

[Table] Value.
As is clear from Table 1, the occurrence rate of abnormally low values due to a considerable amount of captured hydrogen dissipating into the atmosphere was 25% in the conventional sampling tube, but this decreased to 5% in the sampling tube of the present invention. ing. Although not shown in Table 1, the results of combining the ideas shown in Figures 1 to 4 are as follows:
When two or more are used together, the incidence of abnormally low values (for 20 samples) is 0%. Furthermore, the measured values using the sampling tube of the present invention are not affected by hydrogen dissipation, are higher than the measured values using conventional known sampling tubes, and have a lower standard deviation. (Effect of the invention) By using the sampling pipe of the present invention, it is possible to prevent the inorganic refractory wall and the metal conduit from collapsing due to thermal contraction of the sucked up molten steel or the metal conduit during cooling after sucking up the molten steel. This prevents the trapped hydrogen from dissipating through the gaps that occur in the boundary layer, making it possible to obtain accurate hydrogen quantitative values with a high probability, which is useful for metal refining and, ultimately, for metal refining.
This greatly contributes to improving the quality of metal materials.

[Brief explanation of the drawing]

Figure 1 a, b, c, Figure 2, Figure 3 and Figure 4.
Figures a and b are schematic diagrams of the sample collection tube for quantifying the amount of hydrogen of the present invention, Figure 5 is a diagram showing an example of a conventional sample collection tube, and Figure 6 shows the amount of hydrogen collected in the sample collection tube of Figure 5. A schematic diagram showing an example of a gas analyzer for quantifying hydrogen,
Figure 7 is a diagram showing another example of a conventional sample collection tube, and Figure 8 is a collection tube for taking out the hydrogen collected in the sample collection tubes shown in Figures 7a and b and sending it to an analyzer. FIG. 9, which shows a container, is a schematic diagram showing an example of a hydrogen analyzer comprising the collection container and analyzer shown in FIG. 8. In addition, FIG. 1a, FIG. 2, FIG. 3, FIG. 4a, FIG. 6, and FIG. 7a are all longitudinal cross-sectional views.
Figure 1b and c are lines A-A and B in Figure 1a, respectively.
4b is a cross-sectional view taken along line C-C of FIG. 4a, and FIG. 7b is a cross-sectional view taken along line C-C of FIG. 4a.
FIG. 3 is a cross-sectional view taken along line DD of 1... Inorganic refractory wall, 2... Suction port, 3...
...Metal conduit, 4...Cold metal, 5...Vent hole, 6
... Fixed material, 7 ... Residual space, 8 ... Metal ring, 9 ... Low melting point substance, 10 ... Cylindrical opening inner tube, 11 ... Metal ring, 12 ... Thin metal wall, 13 ... ...Cover cap, 14...Mold, 1
5... Vacuum chamber, 16... Gas analyzer, 17... Collection container, 18... Suction base, 19... Collection container,
20... Lid, 21... Bellows, 22... Drive screw, 23... Blade, 24... Fixture, 25... Gas chromatograph-thermal conductivity detection type gas analyzer,
26... Valve, 27... Three-way valve, 28... Heater,
29... Collection container.

Claims (1)

[Scope of Claim for Utility Model Registration] The container wall is made of an inorganic refractory, and one end has a molten metal suction port that is eroded and opened when immersed in the molten metal of the sample, and the inside is open. A conduit made of a hydrogen permeable material is built into the evacuated tubular body so as to communicate with the suction port and form a cavity in which the sucked up molten metal solidifies into a predetermined shape, and In the sampling tube for quantifying the amount of hydrogen in the molten metal, which has a space for accommodating the hydrogen released during solidification and cooling of the molten metal, (a) a protrusion is provided on the outer periphery near the suction port of the conduit; (b) Inserting a low melting point substance into the space between the conduit and the vessel wall; (c) Providing a cylindrical opening inner tube connected to the vessel wall inside the end of the conduit on the suction port side; (d) Wrapping a metal thin plate or wire around the outer periphery of the vessel wall near the suction port; any of the above (a), (b), (c), and (d) alone or in combination; A sample collection tube for quantifying the amount of hydrogen in molten metal, characterized by the following: