JPS6321136B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an apparatus for quantifying diffusible hydrogen in a solid sample, and more particularly to a quantitative apparatus for accurately and simply quantifying trace amounts of diffusible hydrogen in weld metal. Recently, efforts have been made to reduce the amount of hydrogen in the weld metal by improving welding materials and steel materials in order to prevent welding of high-strength steels that are highly susceptible to welding. For this purpose, it is necessary to accurately quantify trace amounts of hydrogen of 2 ml/100 g or less. By the way, the amount of diffusible hydrogen in conventional weld metal is determined according to JIS Z3113-1975 in Japan and IIW (International Institute
of Welding) recommended mercury displacement measurement method (Dec.
-A-275-70).
However, the measurement accuracy of both methods is poor, and the lower limit of quantification is currently not low enough. The present inventors, in order to solve such difficulties,
We have already proposed a method and apparatus for quantifying diffusible hydrogen and residual hydrogen in metals. That is, the present invention is a method and apparatus for quantifying hydrogen in metals, which is characterized in that normal-temperature diffusible hydrogen and residual hydrogen are determined by sequentially controlling valve operations, quantitative determination/recording operations, and the like. According to this, hydrogen of less than 2ml/100g can be determined with high accuracy.
It has become possible to understand the release behavior from 10 ^-5 ml/5min to 10 ^-5 ml/hr. However, there is still considerable room for improvement in this method and apparatus. The room for improvement will be explained below. While hydrogen quantification by conventional heating (or melting) extraction takes 5 to 10 minutes to complete, analysis of diffusible hydrogen requires a long time, e.g.
It requires 72 hours for measurement, and work efficiency is significantly lower. In order to improve this, an attempt may be made to prepare a large number of sample containers, connect them to a single analyzer, and open and close the sample containers manually or automatically using a sequencer for quantification. However, to achieve this, several challenges must be overcome. First, hydrogen released from a sample in a sample container with a constant carrier gas flowing through it will only cause a slight sustained displacement of the baseline in the quantitative results (analog chart) and will not produce the normal peak waveform. , difficult to quantify. Therefore, firstly, in order to have the ability to capture hydrogen that is released little by little over a long period of time, the carrier gas inlet and outlet of the sample container are closed with a valve.
Capable of collecting hydrogen gas for a long period of time. In this case, secondly, hydrogen gas leakage is completely prevented, and thirdly, there is no interference from impure gases such as air when switching the flow paths. Fourthly,
When connecting two or more sample containers to an analyzer, it is necessary that the gas path is completely one continuous path without any dead ends. Fifth, when one sample is placed in a sample container and the released hydrogen gas is collected, or even when the collected hydrogen gas is quantified with an analyzer, it is important to It must be possible to put in and take out another sample. The above has described the case of a manual type, but in the case of an automatic type, in addition to the above-mentioned problems, sixthly, it is necessary that the inlet/outlet valve of the sample container can be easily operated by a sequencer. Seventhly, the time from opening the carrier gas inlet/outlet valve of one sample container until the gas in the container is sent to the analyzer by the carrier gas is as short as possible and there is no difference between the containers. is required. The present invention solves all of the above-mentioned problems and provides an apparatus for accurately quantifying diffusible hydrogen in a solid sample. That is, the present invention includes a flow path switching device constituted by either a six-way valve with a bypass flow path or two three-way valves with a bypass flow path as means for opening and closing the inlet and outlet of the carrier gas, respectively. This is an apparatus for quantifying diffusible hydrogen in a solid sample, characterized in that it is equipped with a sample container, a carrier gas supply means, and a gas analyzer, or in addition, it is equipped with a sequencer. Hereinafter, the present invention will be explained based on the drawings. FIG. 1 shows an embodiment of the apparatus of the present invention. Reference numeral 1 denotes a sample container for collecting hydrogen gas released from a test piece inserted through an insertion port 2. The carrier gas inlet/outlet is opened and closed by two three-way valves 3, 4, and the bypass passage 5 is configured to flow when the inlet/outlet is closed. The sample container system consisting of the sample container 1 and the bypass path 5 can be connected to and disconnected from the carrier gas supply system by means of carrier gas connection joints 6 and 7. 8 is a carrier gas source, the carrier gas is regulated to a constant pressure by a pressure regulating valve 9, and is connected to the sample container system gas line and the alternative carrier gas line 1.
0 and the reference carrier gas path 11. The carrier gas that has passed through the reference carrier gas path 11 is guided to the reference gas side of the analyzer 12. When inserting a sample into the sample container 1 or when separating the sample container system from the carrier gas supply system, close the valves 13 and 14, switch the three-way valve 15, and conduct analysis via the alternative carrier gas line 10. Carrier gas is sent to a total of 12 analytical gas sides. When analyzing hydrogen gas collected in the sample container 1 at a constant temperature for a certain period of time, the sample container system is first connected to the carrier gas supply system through the carrier gas connection joints 6 and 7, and then the valve 1 is connected to the carrier gas supply system.
3 and 14 are opened, the three-way valve 15 is switched so that the alternative carrier gas line 10 is closed and the valve 14 is connected to the analyzer 12, and the carrier gas is allowed to flow through the bypass line 5, and the carrier gas is sent to the sample container system. After purging the impure gas that entered the gas path while it was disconnected from the supply system and confirming this using an analyzer, the three-way valves 3 and 4 are switched to analyze the hydrogen gas in the container 1 using the carrier gas. A total of 12 results are derived and analyzed. FIG. 2 shows another embodiment of the invention. In the figure, numerals 1' to 5' indicate that there is another set that is exactly the same as the sample container 1, insertion port 2, three-way valves 3, 4, and bypass passage 5; Sample container systems 1 to 5 and sample container systems 1' to 5' are arranged in parallel via the sample container systems 1 to 5. When the samples in both containers are both in the hydrogen trapping state, the carrier gas inlets and outlets of sample containers 1 and 1' are connected to three-way valves 3, 4 and 3',
4' and by switching the three-way valves 16, 17 to either of the two sample container system sides, the carrier gas is led to the analyzer 12 via the bypass line 5 or 5'. After collecting hydrogen from the sample for a certain period of time at a certain temperature, first switch the three-way valves 16 and 17 to the target sample container system,
Then, by switching the three-way valves 3, 4 or 3', 4', the hydrogen in the sample container 1 or 1' is sent by carrier gas to the analyzer 12 for analysis. FIG. 3 shows yet another embodiment of the present invention. This embodiment includes an electromagnetic switch 18 for switching to one of two flow paths formed by the sample container 1, the three-way valves 3 and 4, and the bypass path 5;
and a sequencer 19.
The sequencer 19 operates the three-way valves 3 and 4 of the flow path to which the designated container 1 belongs via the corresponding electromagnetic switch 18 after a certain period of time according to a preset sequence program to release the collected hydrogen. is transported to the analyzer 12 by a carrier gas and analyzed. In addition, a flow path to which another container 1' belongs, that is, a valve 3', which was prepared in parallel with this,
Needless to say, the flow path formed by the bypass path 4' and the bypass path 5' can be switched by the electromagnetic switch 18'. In the embodiment described above, the sample container 1
is made of a material that does not permeate hydrogen, such as stainless steel, and the insertion port 2 must be made with an O-ring seal or the like to completely prevent gas leakage. In addition, in the embodiments shown in FIGS. 1 to 3 so far, the carrier gas inlet/outlet opening/closing means of the sample container 1 is formed by the three-way valves 3 and 4 and the bypass path 5 connecting them. However, a six-way valve 20 with a bypass formed to have the same function as shown in Fig. 4 may be used, but it is essential to use an opening/closing means constituted by one of these It is. Furthermore, the fourth
In the figure, solid lines and dotted lines in the six-way valve with bypass 20 indicate the respective gas flow paths when the valve is switched to two positions. As the three-way valve, it is preferable to use an O-ring seal type reciprocating valve, and as the six-way valve with bypass, use an O-ring seal type reciprocating type six-outlet, four-connection valve. Conventionally, in order to provide a similar opening/closing function, two types of regular opening/closing valves 2 were used, as shown in Figure 5.
1 and 22, but in such a means, the container 1 and the on-off valve 2
A joint 6, which connects the sample container system consisting of 1 and 22,
When disconnected from the carrier gas supply system by 7, piping parts 23 and 2 connect to the atmosphere via joints 6 and 7.
The air entering the container 1 causes pressure fluctuations and peak overlap when quantifying the hydrogen in the container 1, resulting in large errors in the measurement results. In order to overcome the above-mentioned drawbacks, as shown in FIG.
It is also conceivable to purge the atmosphere by attaching a flow path consisting of. However, even with this, the piping part 28 becomes a dead end part when purging impure gas such as the atmosphere, and the hydrogen gas in the sample container 1 is
When the sample is led to the tube 2 for analysis, the piping section 29 becomes a dead end, causing tailing and making the quantitative value inaccurate. Moreover, it goes without saying that using a large number of on-off valves for one sample container makes sequence control complicated and difficult. Furthermore, in order to overcome the above-mentioned drawbacks, as shown in FIG. 7, a plurality of sample containers 1, 1', 1''...
A bypass path 32 which opens and closes the carrier gas inlet and outlet of the sample containers 1, 1', 1'', etc. by multi-way valves 30, 31, and leads the carrier gas to the analyzer 12 when all the flow paths passing through the sample containers 1, 1', 1'', . . . are closed. Although it is possible to prevent air from entering and dead ends by arranging a
1', 1'', etc. will leak and the quantitative value will be inaccurate. It is recommended to use swage lock joints for the carrier gas connection joints 6 and 7. Also, as the carrier gas source 8, argon, analytical It is preferable to use a thermal conductivity detection type gas chromatograph for the total 12.Furthermore, a general flow path switching valve can be used for the three-way valves 15, 16, and 17.Sequencer 1
9, it is recommended to use a pinboard programmer. According to the apparatus of the present invention described above, various problems to be solved in connection with long-term collection, namely (i) prevention of gas leakage from the gas inlet/outlet of the sample container, (ii) interference removal of impure gas, and (iii) ) No dead ends in the gas path; (iv) A large number of samples can be analyzed in parallel. Furthermore, in addition to the above-mentioned points, since the time from opening the inlet/outlet valve until the collected hydrogen gas is introduced to the analyzer is constant, it is possible to automatically quantify many samples in parallel using a sequencer. It becomes possible. Finally, the effects of the present invention will be explained in more detail with reference to Examples. Example 1 First, the test material shown in the first column of Table 1 was prepared according to the IIW method, and welded using the welding method shown in the second column and the type of welding material shown in the third column, II
Test piece prepared according to the W method (dimensions are 15 mm wide x 15 mm long x 10 mm high, with two pieces of the IIW method in one piece)
The hydrogen released from the sample (changed to mm) was collected at room temperature for 48 hours and measured using a gas chromatograph using the same procedure as described in connection with FIG.
The measurement results are shown in the fourth column. For comparison, the measurement results using the IIW method are shown in column 5, and the measurement results using the JIS method are shown in column 6. Note that in Table 1, the measured values are displayed in two rows, which represent the results of measurements at two points each. Table 2 shows the detection limits of the generally-known IIW and JIS methods and the detection limits of the present invention based on the quantitative principles, as well as the reproducibility obtained from the measurement results in Table 1 (3 groups depending on the amount of hydrogen). (calculated from /d ₂ according to the usual method) is shown below. As is clear from these comparisons, the detection limit and reproducibility of the method of the present invention are greatly improved compared to conventional methods such as the IIW method and the JIS method, and accurate values can be obtained.

【table】

[Table] Example 2 Two specimens A and B with a shape of 9 mmφ x approximately 14 mm were cut out of carbon steel, polished with emery paper to a weight of 7000 g, and charged with hydrogen by cathodic electrolysis (current density 5 mmA/cm ² ), immediately placed in another sample container after electrolysis, and tested at 5 minute intervals for test piece A and for test piece B as shown in Figure 3.
The amount of hydrogen trapped at room temperature was determined in 10-minute cycles. Table 3 shows an example of the total amount and release rate of collected hydrogen. As can be seen from these results, according to the apparatus of the present invention, it is possible to automatically quantify hydrogen over time up to the hydrogen release rate in a short period of 5 minutes.

[Table] As described above, according to the present invention, it is possible to accurately quantify the amount of room-temperature diffusible hydrogen in a solid sample down to a minute amount, and also to measure the release amount per fixed time, that is, the release rate. Furthermore, multiple samples can be quantified in parallel, either manually or automatically.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are schematic diagrams showing embodiments of the present invention, Figure 4 is a schematic diagram showing an example of a sample container system of the present invention, and Figures 5, 6, and 7. 1 is a schematic diagram showing an example of a general sample container system. 1: Sample container, 2: Insertion port, 3, 4, 15, 1
6, 17: 3-way valve, 5, 27, 32: bypass path, 6, 7: carrier gas connection joint, 8: carrier gas source, 9: pressure regulating valve, 10: alternative carrier gas path, 11: reference carrier gas path, 1
2: Analyzer, 13, 14, 21, 22, 25, 2
6: Valve, 18: Solenoid switch, 19: Sequencer, 20: 6-way valve with bypass, 23, 24, 2
8, 29: Piping dead end portion, 30, 31: Multi-way valve.

Claims (1)

[Claims] 1. A six-way valve with a bypass flow path as means for opening and closing the inlet and outlet of the carrier gas, respectively;
or a sample container equipped with a flow path switching device constituted by either one of two three-way valves with bypass flow paths, and a carrier gas feeding means for transporting the hydrogen gas collected in the sample container. An apparatus for quantifying diffusible hydrogen in a solid sample, comprising: a gas analyzer for separating and quantifying hydrogen gas carried by a carrier gas. 2. A six-way valve with a bypass flow path as a means for opening and closing the inlet and outlet of the carrier gas, respectively;
or a sample container equipped with a flow path switching device constituted by either one of two three-way valves with bypass flow paths, and a carrier gas feeding means for transporting the hydrogen gas collected in the sample container. , a solid body comprising a gas analyzer for separating and quantifying hydrogen gas carried by a carrier gas, and a sequencer for operating the flow path switching device according to a preset sequence program. Device for quantifying diffusible hydrogen in samples.