JPH0599843A - Sampler for steel production - Google Patents

Abstract

PURPOSE:To enable a working efficiency to be improved and a working load to be reduced by specifying a distance between a thermocouple for measuring temperature of a melted steel and a pin sampler for analysis within the melted steel [C] which are fixed in one piece in parallel and an exposure length of the pin sampler. CONSTITUTION:A platinum - platinum rhodium thermoelectric band is used for a thermocouple 5, a distance between an iron protection gap and a vacuum crystal tube 7 is important in terms of temperature-measuring accuracy and for sampling an improved sample by a pin sampler. For example, when this distance is equal to or less than 17mm, a measured temperature becomes lower than an actual temperature due to an influence of a slug which is adhered to a side of the pin sampler which is fixed in parallel and a metal steel temperature at a side of the pin sampler. Therefore, this distance needs to be equal to or more than 17mm. Also, a sealing glass is used at a tip part where the melted steel enters for the crystal tube 7 and this tip part is controlled to be extremely thick. An exposure length from a trunk of the crystal tube 7 is important at this part and a length of 18mm-30mm is proper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steelmaking sampler used in a production method for controlling the C component in a steel in a narrow range, and particularly to a JIS G3502 piano. It is a sampler for steelmaking used in a method for adjusting a C component for the purpose of reducing variations in strength of a wire rod and JIS G3506 hard steel wire rod and joining steel types.

[0002] In order to guarantee quenching hardness within a narrow range in a structural steel material having a JIS G4052 hardenability, it is necessary to control the C component, which has a particularly large influence, within a narrow range. Used in cases.

[0003]

2. Description of the Related Art Conventionally, in a refining furnace for steelmaking, a sample for component analysis has a diameter of about 25 mm and a height of about 5 mm.
It is common to sample about 5 mm before use. As a means for measuring the molten steel temperature in the refining furnace, using a thermocouple type thermometer, it is generally used independently of the steel-making sampler for collecting the sample for component analysis, but recently, the above In some cases, the sampler and the thermometer are fixed and integrated.

[0004]

As a problem of the prior art, the sample for component analysis has a diameter of about 25 mm and a height of about 5 mm.
It is a so-called bomb sample of about 5 mm and is usually used for emission spectroscopic analysis (cant back analysis). Since this sample is relatively large and solidification takes a long time, segregation of the C component becomes large especially in the circumferential direction and the height direction. In addition, the emission spectroscopic analysis had an error and the analysis accuracy was poor as compared with the combustion-infrared absorption method (chemical analysis), and in combination with this, the narrow range control accuracy of the C component was limited. That is, ± 0.0 in 0.80% C steel
The accuracy rate in the range of 1% was low at 90% or less. Generally, sampling of a sample for component analysis and temperature measurement by a thermocouple type thermometer are conventionally performed separately, which requires a long working time and a large work load.

[0005]

Means for Solving the Problems The present invention advantageously solves the problems of the prior art. (1) In a steelmaking sampler for sampling molten steel samples and determining molten steel components, (2) A steel sampler comprising a bomb sampler for analyzing a molten steel component, a thermocouple for measuring a molten steel temperature, and a pin sampler for analyzing a molten steel [C] in the bottom of the bomb sampler, which are fixedly installed in parallel.
In the steelmaking sampler according to the item (1), a distance β between a thermocouple for molten steel temperature measurement and a molten steel [C] analysis pin sampler that are solidly installed in parallel is 17 mm or more, and a molten steel [C] analysis pin is used. Pin exposure length α of the sampler is 18 ~
A steelmaking sampler having a length of 30 mm.

The present invention will be described below with reference to the steelmaking sampler of the embodiment shown in FIG.

In the figure, reference numeral 1 denotes a paper tube which forms an outer frame of the sampler and has a role of preventing intrusion of slag and molten steel.

Reference numeral 2 is a template, and the bomb sample collected here is analyzed by emission spectroscopy for components other than C. In this figure, the shape is a bomb shape, but it may be a disk shape.

Reference numeral 3 is a chamber, 4 is a heat insulating material, and 5 is a thermocouple. A platinum-platinum rhodium thermocouple is used. The distance between the iron protective cap and the vacuum quartz tube (pin sampler) 7 is the temperature measurement accuracy. It is important to obtain a good sample with a pin sampler. As clearly stated in the examples, when the distance is 17 mm or less, the temperature becomes lower than the actual temperature due to the influence of the slag adhering to the pin sampler side fixed in parallel and the molten steel temperature on the pin sampler side. Turned out to be measured. Therefore, this distance is 17mm
The above is necessary.

Reference numeral 6 denotes a trunk, which is a holder for a pin sampler. Although this material is a magnetic material, if an iron material is used, molten steel slag will adhere to this portion immediately after the sampler enters the molten steel in the refining furnace, making it impossible to take a sound sample. Further, since the temperature of the thermocouple fixed in parallel becomes low, the use of iron material is not suitable.

Reference numeral 7 is a vacuum quartz tube (pin sampler), and a sealing glass is used at the tip of the molten steel, and the tip is controlled to have an appropriate thickness. In this portion, the exposed length of the vacuum quartz tube from the trunk is important, and a length of 18 to 30 mm is suitable as shown in the examples.

The inner diameter of the pin sampler is preferably 10 mmφ or less in order to rapidly solidify.

Reference numeral 8 is a chill, 9 is a refractory mortar, and 10 is a heat resistant adhesive. Reference numeral 11 denotes an iron cap, which is usually a thin iron plate.

The reason for using the pin sampler for C analysis and cutting the pin sample for analysis by the combustion-infrared absorption method (chemical analysis) has been described above with reference to the drawings.

The bomb sample used for emission spectroscopic analysis has a large diameter of about 25 mm and a height of about 55 mm, and since solidification takes a certain time, segregation of components occurs in the circumferential direction and the height direction. Fig. 2 shows the measured values for high-carbon steel. The average C value = 0.740% variation (δ) =
The variation in C value within the sample is 0.012%, which is very large.

The emission spectroscopic analysis method has poor repetitive analysis accuracy as compared with the combustion-infrared absorption method. As a result of both investigations, in the case of 0.80% C material, the variation (δ) in the emission spectroscopic analysis method was 0.005%, and the variation (δ) in the combustion-infrared absorption method was 0.003%.

For the above reasons, in order to control the C component within a narrow range, a pin sampler is used to solidify in a short time to reduce the component segregation and the combustion with good repeatability. It is essential to use the infrared absorption method.

Further, the reason why the bomb sampler, the thermocouple for temperature measurement, and the pin sampler for analysis [C] are fixedly integrated is that it takes time for individual sampling and temperature measurement. It is integrated in order to avoid the possibility of prolonging the time, increasing the work load for this, and increasing the cost of temperature measurement and sampler.

[0019]

EXAMPLES Examples are shown in Table 1. 4, No.
5, No. 6, No. 8, No. 9 shows the present invention, the holder material of the pin sampler is a ceramic material, and the exposed length of the pin sampler is 18 to 30 mm,
The distance between the pin sampler and the thermocouple is 17 mm or more.

That is, by using a ceramic material as the holder material, less molten steel or slag adheres to this portion, and the exposed length of the pin sampler is 18 to
Since it was installed in an appropriate range of 30 mm, the molten steel was sucked into the pin sampler without being affected by the adhered metal or adhered slag at the tip of the pin sampler. Sampling was performed without any breakage. Regarding the molten steel temperature, a wide distance between the pin sampler and the thermocouple of 17 mm or more was ensured, so that favorable temperature measurement was performed without being affected by the pin sampler side.

On the other hand, the defective No. 1, No. With respect to No. 2, because the pin exposed length and the distance between the pin sampler and the thermocouple were short, sample defects and temperature defects were caused. No. Regarding No. 3, the sample was good because the pin exposed length was sufficient as 20 mm, but it was lower than the actual temperature because the distance between the pin sampler and the thermocouple was as short as 15 mm.

No. 7 has a pin exposed length of 35
It is considered that the sampler was broken due to insufficient strength due to the impact when the sampler entered the molten steel surface.

No. 10, No. 11, No. In No. 12, the holder material of the pin sampler is made of iron, and it is considered that the solid steel could not be taken due to the adherence of molten steel or slag to this portion, and the temperature also became low due to this influence.

[0024]

[Table 1]

[0025]

INDUSTRIAL APPLICABILITY The present invention, when analyzing [C] in molten steel,
The accuracy of the narrow range control of the (C) component was poor in the bomb sample-emission spectroscopic analysis that was generally performed in the past, whereas the narrow range control of the (C) component was performed by the pin sample-combustion / infrared absorption method. The accuracy has been greatly improved.Since the pin sampler is fixedly integrated with the bomb sampler and thermocouple, it has been customary in the past to sample the sample for component analysis and temperature measurement separately. In contrast to this, it was possible to extend the work time and reduce the work load by enabling the pin sample and bomb sample to be sampled and temperature measured at the same time in a single operation.

By applying the pin sample-combustion / infrared absorption method, as shown in FIG. 2, the narrow range control accuracy of the component (C) was greatly improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a steelmaking sampler according to an embodiment of the present invention.

FIG. 2 is a distribution chart of finish C value in high carbon steel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper tube 2 ... Mold 3 ... Chamber 4 ... Insulating material 5 ... Thermocouple 6 ... Trunk 7 ... Vacuum quartz tube 8 ... Chilled money 9 ... Refractory mortar 10 ... Heat-resistant adhesive 11 ... Iron cap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichinori Kawahara 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Steel Works

Claims (2)

[Claims] 1. A steelmaking sampler for the purpose of sampling molten steel samples to determine molten steel components,
A steelmaking sampler comprising a bomb sampler for analyzing a molten steel component, and a thermocouple for measuring a molten steel temperature and a pin sampler for analyzing molten steel [C] at the lower part of the bomb sampler in parallel and fixedly integrated. 2. The steel sampler according to claim 1, wherein the distance β between the thermocouple for molten steel temperature measurement and the pin sampler for molten steel [C] analysis, which are integrally fixed in parallel, is 17 m.
A sampler for steelmaking, characterized in that the pin exposed length α of the pin sampler for analysis in molten steel [C] is 18 to 30 mm.