JPS5827866B2 - Method and device for determining hydrogen in metals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for quantifying hydrogen in metal, and in particular to a method and apparatus for easily and automatically quantifying trace amounts of hydrogen in deposited metal obtained during welding. The present invention relates to a measuring method and apparatus for the purpose of.

Recently, efforts have been made to reduce the amount of hydrogen in the weld metal by improving welding rods and steel materials in order to prevent welding of high-strength steel, which is considered to be highly susceptible to welding.

For this purpose, it is necessary to accurately quantify the trace amount of hydrogen in the deposited metal of 2 tull/1001 or less.

By the way, in Japan, when measuring the amount of diffusible hydrogen in conventional weld metal, it is common practice in Japan to use the JIS method, which uses glycerin substitution.
Z3113-1975 method for measuring the amount of hydrogen in weld metal is widely used.

On the other hand, in various countries around the world, I, I
, W(International In5titu
te of welding) measurement method (Doc, I
I-A-275-70) has been widely adopted.

Comparing the JIS method and the IIW method, the JIS method has the great advantage of not using mercury, which is harmful to the human body, but it has been reported that the measured value is about 40% lower than the IIW method. ing.

The reason for such a low value is that the floating speed of small hydrogen bubbles released from the test piece into glycerin is extremely slow (approximately 1/10' slower than in mercury).
It is thought that the particles could not be completely floated to the surface during the collection time of 8 hours and remained as small bubbles.

Furthermore, it has been pointed out that hydrogen has a small solubility in glycerin.

In addition to errors caused by the collecting liquid, test materials, welding conditions, atmospheric cooling conditions, etc. can be considered as fluctuation factors, but the variation σ caused by these is 0.5 vertical/10
At around 0g, it is approximately 1al that can be determined by repeating n=4.
It is said to be /100&.

On the other hand, 1.1. The W method has the fatal disadvantage of having to handle a large amount of mercury, which is harmful to the human body, as well as the fact that air enters the measuring container through the joints during the 72-hour period under reduced pressure of 10 Hg. Measurements often end in failure.

1.1. The variation σ of the measured values by the W method is approximately 0.5tr
It is said to be tll/1001i', and the lower limit of quantification is approximately 2d/100g.

This lower limit of quantification is determined by visually measuring the gas collected in a billet with a minimum scale of 0.05/ItJ and from the fact that the amount of deposited metal is approximately 1 g.

On the other hand, in addition to hydrogen in the deposited metal, the amount of hydrogen in the molten metal during welding also provides important knowledge for elucidating the phenomenon of weld warpage.

As a method to elucidate the hydrogen dissolution process in molten metal,
For example, Mr. G. R. 5alter of the United Kingdom (Britis)
hWelding Journal, June 19
63 P 316-325), steel is arc melted in a closed container filled with a mixed gas of argon and hydrogen, and immediately after the arc is extinguished, the molten steel is guided into a separate chamber isolated from the arc chamber in a closed container, where it is melted. reported a method for quantifying hydrogen released as hydrogen solubility decreases due to cooling and solidification of molten steel (maximum elapsed time after arc extinction is 45 seconds) using a thermal conductivity meter.

According to this method, 0.2 to 1
．． 2/Itl(N,T,P), i.e. 2tttl! 7
It is possible to quantify approximately 100 g to 12 d/100 g of hydrogen, but the maximum error is said to be ±0.007 m/(approximately 0.1 m//100 f).

From the viewpoint of whether this method can be used to quantify hydrogen in the weld metal mentioned above, this method can be used in a short period of about 45 seconds after the arc is extinguished. ~
It was developed for the purpose of quantifying hydrogen released in large amounts (12rrtl/100g), and is therefore unsuitable for quantifying hydrogen in weld metal.

In this way, in addition to the shortcomings mentioned earlier, none of the three methods mentioned above meet the requirements for measuring trace amounts of hydrogen in weld metal as mentioned above in terms of lower limit of quantification and quantification accuracy. do not have.

In addition, when determining the amount of residual hydrogen, after measuring diffusible hydrogen using the JIS method or IIW method, the same test piece is subjected to operations such as cutting, cleaning, and drying. Quantification is performed using a hydrogen quantification device.

However, it is very complicated to measure diffusible hydrogen and residual hydrogen using different devices and different operations on the same test piece.

The present invention solves all of these difficulties and provides a method and apparatus for automatically and accurately quantifying trace amounts of diffusible hydrogen and residual hydrogen in weld metal.

That is, the present invention has the following features: (1) A hydrogen collection container is provided intermittently in a hydrogen quantitative system in which a carrier gas is constantly allowed to flow, and a test piece inserted into the collection container collects diffusible hydrogen at a constant rate. After releasing the hydrogen into the container for a certain amount of time, the hydrogen is introduced into the gas analyzer using the carrier gas and quantitatively determined.This is repeated an arbitrary number of times, and the time per analysis cycle, the number of cycles, and the required amount are determined. 1. A method for quantifying hydrogen in metals, characterized in that normal temperature diffusible hydrogen is determined by sequence control of valve operations and quantitative/recording operations.

and (2) A hydrogen collection container is provided intermittently in a hydrogen quantitative system in which a carrier gas is constantly supplied, and diffusible hydrogen is released into the container for a certain period of time from a test piece inserted into the collection container. After this, the hydrogen is introduced into a gas analyzer using the carrier gas and quantified. This is repeated an arbitrary number of times, and the time per analysis cycle, number of cycles, required valve operations, and quantification are determined.

The recording operation is performed under sequence control to quantify room temperature diffusible hydrogen, then the container is evacuated, the test piece in the container is heated for a certain period of time to release residual hydrogen, and then a carrier gas is injected into the container. A metal characterized in that hydrogen is introduced into an analyzer to bring the pressure to approximately normal pressure, and the residual hydrogen is determined by introducing the hydrogen into an analyzer and quantifying it, and performing necessary valve operations and quantitative/recording operations by sequence control. Method for quantifying hydrogen in

and an apparatus for implementing these, which according to the present invention is capable of accurately quantifying hydrogen of 2 m171009 or less, and which is capable of quantifying hydrogen at a rate of 10"tttl/5 min or 10"
``It is possible to understand the behavior of trace amounts of released hydrogen up to about trtl/hl.

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 collection container into which a test piece is inserted to collect hydrogen released at room temperature, and is held in a heating furnace 2 whose temperature can be controlled by a temperature indicating controller 12 via a changeover switch 13. The collection container 1 is connected to the gas flow path of the hydrogen quantitative system via an artificial valve 3 for introducing carrier gas and an outlet valve 4 for extracting the carrier gas and the collected hydrogen. It is connected to the.

Ar gas, N2 gas, or the like is used as the carrier gas, and the carrier gas is supplied from the cylinder 5 while being adjusted in flow rate by the flow rate control valve 6.

7°8 is a switching valve for switching the carrier gas flow path to an arbitrary collection container 1 or 1; 7 is a gas flow path population valve 3;
8 are respectively connected to the gas flow path outlet valve 4 side.

The switching valve 8 is collected in the collection container 1 or 1',
This is for guiding the hydrogen guided by the carrier gas to the gas analyzer 9.

The analyzer 9 is connected as analysis data recording means to a recorder 10 for analog recording of the measured values of the quantitative analysis and an integrator 11 for recording the integral amount of the measured values.

The collection container 1 is connected to a vacuum exhaust device 14 via a valve 15. The pipes are designed to allow for exhaust air.

Further, a valve 16 is interposed between the cylinder 5 and the collection container 1 to shut off the cylinder 5 when the collection container 1 is evacuated.

The heating time and temperature of the heating furnace 2 are controlled as described above, the hydrogen gas collection time in the collection container 1 is controlled, and the hydrogen gas collected in the collection container 1 is sent to the gas analyzer 9. control of the flow path and timing of the carrier gas, control of the start and stop of operation of the recorder 10 and the integrator 11 in accordance with the timing of introducing the sample gas from the collection container 1 to the gas analyzer 9, and control of the operation start and stop of the recorder 10 and the integrator 11, and The sequence control mechanism 17 controls the evacuation device 14 and valves 15 and 16 for evacuation of the collection container 1 and introduction of carrier gas for quantitative determination.

In addition to the carrier gas, the embodiments of the apparatus described above are equipped with a collection container, a gas analyzer, an analysis data recording means, and a sequence control mechanism, or a heating furnace and its temperature control mechanism, and a vacuum evacuation device. It is essential to do so, and the arrangement of valves, piping system, etc. can be changed as appropriate.

In addition, in FIG. 1, the collection units with the same configuration are 1',
This is an example of another set of units such as 2', 3', 4', etc., and it is of course possible to arrange multiple sets of similar units other than those shown.

In such a case, temperature control of each heating furnace is performed by the changeover switch 13.

It is important that the material of the gas collection container 1 has sufficient strength at temperatures up to 1300°C and is impermeable to hydrogen, and that the internal put space is 20 d or less. desirable.

Further, it is necessary to select a heating furnace 2 that can raise the temperature to about 1300° C. or higher.

Note that a normal temperature indicating controller can be used.

The gas analyzer 9 analyzes the hydrogen carried by the carrier gas at least 1 x 10'al (N, T,
It is necessary to quantify up to P, ), for example, using a thermal conductivity detection type gas chromatograph.

The integrator 11 is free from disturbances such as quantitative noise caused by pressure fluctuations caused by the opening and closing of valves for conveying carrier gas due to fluctuations in the baseline accompanying long-term operation of the gas analyzer 9, and is capable of measuring the target gas. It is desirable to use, for example, a digital inch break for gas chromatography, which is capable of integrating only the analytical peaks.

Note that as the analog recorder, for example, a normal pen recorder can be used.

The evacuation device 14 must be capable of evacuation to at least 10 -1 Hg.

It is important for the sequence control mechanism 1γ that the starting switch for operating the valve or switch etc. performs the connection/disconnection operation at an arbitrarily set time, and the format is as follows:
For example, a pinboard programming method can be used.

Next, the procedure for implementing the method of the present invention using the apparatus of the present invention shown in Embodiment 1 of FIG. 1 will be explained.

First, a typical test piece preparation method such as 1.1. W, law (D
oc, n-A-275-70, 6, 1 Specimen Preparation for Analysis).

A test piece is placed in a collection container 1 held in a heating furnace 2, and after the air in the container 1 is purged with a carrier gas as required, the population valve 3 and outlet valve 4 are closed.

When the inlet valve 3 and the outlet valve 4 are closed, only the carrier gas is guided to the gas analyzer 9 by the inlet switching valve 7 and the outlet switching valve 8.

After a preset time has elapsed, the sequence control mechanism 17 opens the inlet valve 3 and the outlet valve 4, and further operates the inlet switching valve 7 and the outlet switching valve 8, so that the sample is released from the test piece and into the container 1. The stored hydrogen is guided from the carrier gas cylinder 5 to the gas analyzer 9 by the carrier gas via the valve 6.

The sequence control mechanism 17 includes a recorder 10 and an integrator 11
and operate respectively.

The amount of hydrogen in the container 1 is recorded by the recorder 10 as an analog signal, and by the integrator IH as an integrated digital amount after correcting baseline fluctuations.

After the analysis is completed, the sequence control mechanism 1T closes the inlet valve 3 and outlet valve 4 of the container 1 again, operates the inlet switching valve 7 and the outlet switching valve 8, and guides only the carrier gas to the gas analyzer 9.

The time from opening the large mouth valve 3 until the integrator 11 starts operating is set in advance.

After an arbitrary preset time has elapsed, the sequence control mechanism 17 repeats the same analysis cycle again.

As a result, after the first analysis, the amount of hydrogen released into the container 1 is quantified.

The sequence control mechanism 17 controls this analysis cycle in advance.
Repeat the specified number of times to complete the quantitative operation of room-temperature diffusible hydrogen (as a general rule, the extraction time is
, I, W, and G, it is best to set it as 72 hours)
.

The sum of the amounts of hydrogen obtained in each analysis cycle gives the room temperature diffusible hydrogen.

Next, the vacuum evacuation device 14 is operated to open the valve 15, the container 1 is evacuated, and the valve 15 is closed again.

Activate the temperature indicator controller 12 and heat the heating furnace 2 to 1300°C.
After raising the temperature to an arbitrary temperature below and indirectly heating the test piece in the collection container 1 to release the remaining hydrogen for an arbitrary fixed period of time, the valve 16 is opened to introduce carrier gas. After setting the pressure to normal pressure, close the valve 16 again, then operate the inlet switching valve 7 and the outlet switching valve 8 to open the large mouth valve 3 and the outlet valve 4 to remove the hydrogen released at high temperature by the carrier gas. The high-temperature released hydrogen led to the gas analyzer 9 is also recorded in the same way as the normal-temperature released hydrogen (this is recorded in analog and digital amounts).

In this case, by setting the heating temperature in any number of steps, it is also possible to separately quantify residual hydrogen by extraction temperature.

Regarding the above operations, for example, when the hydrogen from the collection container 1 is not being analyzed by the gas analyzer 9 using exactly the same sequence control, the collection container 11, the heating furnace 21, the large mouth valve 3'
, operating the outlet valve 41 to guide the hydrogen from the collection vessel 1' to the gas analyzer 9 (thus, two test pieces are used to obtain similar measurements in the same amount of time). Is possible.

Therefore, as mentioned above, if multiple sets of extraction units with the same configuration are arranged, the method described above (thus, for a large number (r+>2) of test scissors, the amount of diffusible hydrogen for each It is possible to simultaneously quantify the amount of residual hydrogen with high accuracy down to the trace amount.

If necessary, it is also possible to obtain useful microscopic measurements such as the amount of hydrogen released per unit time (see Figure 2) or the amount of extracted hydrogen at each heating temperature (see Figure 3) regarding residual hydrogen. .

It goes without saying that if the amount of hydrogen released per unit time or the amount of hydrogen extracted per heating temperature is unnecessary, the analysis operation can be simplified to obtain only the measured value of interest.

The device example shown in FIG. 1 shows only one aspect of the present invention, and the present invention may include a mass spectrometer instead of a gas chromatograph, a cam programmer instead of a pinboard programmer, etc. within the scope of the claims.
Needless to say, things can change.

Furthermore, if quantitative determination of residual hydrogen is not particularly required, it is a matter of course that the equipment and operations related thereto can be omitted.

Finally, the present invention will be explained in more detail with reference to Examples.

Example 1 First, the test materials shown in the first column of Table 1 were subjected to 1.1. Prepared according to the W method and welded using the welding method shown in the second column using the type of welding material shown in the third column, 1.1. Test piece prepared according to the W method (dimensions are 1.1. Two pieces of the W method are taken as one piece, width 15
15 mm long x 15 mm long x 10 mm high) was measured using a gas chromatograph at room temperature in 1-hour cycles by performing the same operation as explained in Figure 1, and this was repeated 48 times to measure each The total of the results is in the fourth column, 1000
Column 5 shows the total of the results of heating extraction at ℃ and analysis twice at 30 minute intervals.

For reference 1.1. The measurement results using the W method are shown in column 6, and the results are shown in column 6.
, 1. The measurement results by the S method are shown in column 7.

Based on the principle of quantitative determination, Table 2 shows the lower detection limits of the generally known IIW method and JIS method and the lower detection limit of the method of the present invention, as well as the reproducibility obtained from the measurement results in Table 1 (depending on the amount of hydrogen). Divide into groups and show a comparison of ``calculated from force 2'' according to the usual method.

As is clear from these comparisons, the method of the present invention lowers the absolute detection limit of hydrogen by three orders of magnitude compared to conventional methods such as the IIW method and the JIS method, and also lowers the relative measurement value (taking into account the amount of sample collected). trtl/100!), the method of the present invention greatly improves the conventional method in comparing the lower limit of quantification, which takes into account the overall reproducibility including the mechanism of hydrogen intrusion through the weld bead. However, it can be seen that not only is it possible to quantify diffusible hydrogen in the low concentration range, but it is also possible to obtain more accurate values than conventional methods even in the trace amount range.

Example 2 Test piece A made of carbon steel with a shape of 9 mm φ x approximately 14 mm
, B, C, D, E, and F, finished polishing with emery $600 to a weight of 7,0 OOP, and lN-H2SO
1, 5, 10, 5, respectively, at a current density of 5 mA/ad using a platinum mesh as a counter electrode in a solution containing 46 pieces of A35rI19.
Constant current cathodic electrolytic hydrogen charging was carried out for 0, 100, and 500 minutes. Immediately after electrolytic charging, the test piece was placed in the collection container 1 shown in FIG. 1, and measurements were repeated 48 times at room temperature every hour.

The total of each measurement value is shown in Table 3.

Table 4 also shows changes in the amount of hydrogen released over time for two samples of F.

As can be seen from this result, according to the method of the present invention, 0,000
013i or 0.0000277! It is possible to automatically quantify the amount of released hydrogen down to an infinitesimal amount of 1,000 liters over time, and even the total released amount obtained by adding them up is 0.000, which was difficult with conventional methods.
It is possible to measure up to a trace amount of hydrogen of 0.056 yrtl.

As is clear from the above examples, the present invention not only makes it possible to accurately and accurately automatically quantify the amount of diffusible hydrogen of 2rnl/100 f or less, which was difficult to measure in the past, but also Hydrogen can also be measured easily and automatically with high precision, and the amount of hydrogen released per specific time can be measured at 0.00001 for each short period of 5 minutes.
It is possible to grasp minute amounts down to mg, thereby clarifying the microscopic behavior of hydrogen release, which is extremely important in contributing to ensuring the safety of metals and metal structures.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the principle of the device of the present invention, Fig. 2 is a diagram showing the relationship between the amount of hydrogen released per unit time, the cumulative amount of captured hydrogen, and the collection time obtained using the device of the present invention, and Fig. 3 The figure is a diagram showing the relationship between the cumulative amount of trapped hydrogen obtained using the apparatus of the present invention and the heating temperature. 1, 1': Gas collection container, 2, 2': Heating furnace,
3゜31: Inlet valve, 4, 4': Outlet valve, 5: Carrier gas cylinder, 6: Flow rate control valve, 1: Inlet switching valve, 8
: Outlet switching valve, 9: Gas analyzer, 10 Recorder 1
1: Integrator, 12: Temperature indicating controller, 13: Selector switch, 14: Vacuum exhaust device, 15゜15': Valve, 16,1
6': Valve, 11 nitrogen control mechanism.

Claims (1)

[Claims] 1. A hydrogen collection container is provided intermittently in a hydrogen quantitative system in which a carrier gas is constantly supplied, and diffusible hydrogen is collected for a certain period of time from a test piece inserted into the collection container. After being released into the container, the hydrogen is introduced into a gas analyzer through the carrier gas and quantified, and this is repeated an arbitrary number of times, and the time per analysis cycle is
A method for quantifying hydrogen in metals, characterized in that room temperature diffusible hydrogen is determined by sequentially controlling the number of cycles, required valve operations, and quantitative/recording operations. 2. A hydrogen collection container is installed intermittently in a hydrogen quantitative system in which a carrier gas is constantly supplied, and after diffusible hydrogen is released into the container for a certain period of time from a test piece inserted into the collection container. , the hydrogen is introduced into the gas analyzer using the carrier gas and quantified, and this is repeated an arbitrary number of times, as well as the time per analysis cycle, the number of cycles, the required valve operations, and the quantification/recording operations. Quantify room temperature diffusible hydrogen by sequence control,
The container is then evacuated, and the test piece in the container is heated for a certain period of time to release residual hydrogen. Next, a carrier gas is introduced into the container to bring it to approximately normal pressure, and the hydrogen is transferred to an analyzer. A method for quantifying hydrogen in a metal, which is characterized in that the residual hydrogen is determined by sequentially controlling the necessary valve operations and 4-row operation. The hydrogen quantitative system includes a supply source of the carrier gas, a collection container for holding the test piece and collecting hydrogen released from the test piece, an analyzer for quantifying the amount of hydrogen, and An apparatus for quantifying hydrogen in metals, comprising means for recording the results, a plurality of valves for appropriately switching gas flow paths, and a sequence control mechanism for controlling these analysis operations.4. A hydrogen quantitative system in which a carrier gas is constantly supplied, comprising a supply source of the carrier gas, a collection container for holding a test piece and collecting hydrogen released from the test piece, and the collection An exhaust device for evacuating the container, a heating furnace for heating the test piece, an analyzer for quantifying the amount of hydrogen, a means for recording the results, and a means for appropriately switching the gas flow path. An apparatus for quantifying hydrogen in metals, comprising a plurality of valves and a sequence control mechanism for controlling these analytical operations.