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A hydrogen peak of internal friction and its isotope effect in austenitic stainless steel
Scripta METALLURGICA
A HYDROGEN
Vol. 19, pp. 47-50, 1985 Printed in the U.S.A.
Pergamon Press Ltd. All rights reserved
PEAK OF INTERNAL FRICTION AND ITS ISOTOPE EFFECT IN AUSTENITIC S. Asano
STAINLESS
and
STEEL
M. Kazaoka
Department of Metallurgical Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
(Received
September
12, 1984)
Introduction In austenitic stainless steels such as SUS 310S, SUS 316 and SUS 304, an internal friction peak due to dissolved hydrogen has been found at about 300 K by Asano et al.(l-3) and confirmed by Igata et al.(4). As has been reported in a previous paper (2), its peak height increases with the hydrogen concentration while its peak temperature remains constant. This internal friction peak is characterized by the same activation energy as that of hydrogen diffusion (3) but never affected by cold work (4,5). Although its mechanism is not known in detail, it has been attributed to a Snoek-type relaxation of hydrogen atom-pairs reorienting in the fcc Fe-Cr-Ni lattice (2, 3). This is analogous to the hydrogen peak of internal friction in fcc Pd-H (6), hcp Lu-H (7) and fcc Fe-Ni-H alloys (8,9). Such an internal friction peak may provide useful information on hydrogen diffusion. For a similar type of austenitic stainless steel, Quick and Johnson (i0) have made a precise measurement of hydrogen and deuterium diffusion over the temperature range from 472 K to 779 K. They have found an isotope effect; the ratio of the diffusion coefficients of hydrogen to deuterium, DH/DD, is near to ~-~-, which is the value predicted by classical theory. Meanwhile, in pure nickel (Ii) and its dilute alloys (12), the measured value of DH/D D is known to be temperature-dependent, deviating remarkably f r o m ~ at lower temperatures. It is therefore necessary to examine the isotope effect of hydrogen diffusion in austenitic stainless steel in the temperature range lower than that of Quick and Johnson. The purpose of this study is to detect hydrogen and deuterium peaks of internal friction in austenitic stainless steel and to determine the value of DH/D D at about 300 K on the assumption of a Snoek-type relaxation. The isotope effect will be revealed as the difference in the peak temperature between hydrogen and deuterium. Experimental
Procedure
The experimental conditions for deuterium were almost the same as those adopted previously for hydrogen (2,3). The material used was a commercial austenitic stainless steel designated as SUS 310S ( Fe-25%Cr-20%Ni ), which is known as a stable fcc alloy. It was machined into plate specimens in various sizes; 54-90 mm in length, 0.53-1.41 mm in thickness and i0 mm in width. All the specimens were solution-treated for one hour in vacuum at 1323 K and then quenched into iced water. The specimens were electrolytically charged with hydrogen at room temperature. The electrolytes used were IN H2SO4-H20
47 0036-9748/85 $3.00 + .00 Copyright (c) 1985 Pergamon Press Ltd.
and deuterium solution for
48
INTERNAL FRICTION IN STAINLESS STEEL
Vol. 19, No. I
hydrogen charging and IN D2SO4-D20 solution for deuterium charging, both of which were poisoned with 250 mg As20 3 per liter. The current density was 500 A/m 2 and the charging time was 20 hours. According to Farrell and Lewis (13), the concentration of hydrogen or deuterium might be 0.5-0.8 atoms per metal atom in the near-surface region before the measurement of internal friction. Internal friction was measured by the free decay method in transverse vibration in the temperature range from 160 K to 370 K at a heating rate of 0.017 K/s. The testing frequency varied from 300 Hz to 2300 Hz by changing the specimen size. Under these conditions, the peak temperatures are expected to lie within the range of 290-320 K. Results and Discussion FIG.I shows the internal friction peaks caused by hydrogen charging and by deuterium charging, which were measured at nearly equal frequencies. The height and position of the hydrogen peak were entirely consistent with the previous results (2,3). On the other hand, the deuterium peak had almost the same height but was apparently located at a temperature 4-5 K higher than the hydrogen peak. The difference in the peak temperature may result from an isotope effect between hydrogen and deuterium, as observed in palladium (6) and lutetium (7). It should be noted that the peak temperature does not depend on the hydrogen concentration (2,5), nor possibly on the deuterium concentration. FIG.2 shows the Arrhenius graph relating the reciprocals of peak temperatures to the logarithms of vibrational frequencies. The solid line in this figure is an Arrhenius relation for the hydrogen peak, which has been reported by Asano et al.(3) over the temperature range from 230 K to 310 K. This yields the activation energy E = 49.0 kJ/mol and the frequency factor Tp /
310 SUS310S 6
o Hydrogen •
1 0 '~
~'Oo,. oe
Deuterium
° e
oe
t~O
10 3
o.
8
°e
ARRHENIUS PLOT
*O
0 •
Hydrogen Deuterium
102
::
101
~%"
2
220 ,
o
~.
o
240 ,
N "r
oe
T
K
260 ,
° oe
°e
"-4
,
,~
°e
°e
280 ,
o ~" ~oooOe~%~ •
0 150
I
200
I
1
a
250 300 350 400 T / K FIG. 1 Hydrogen and deuterium peaks of internal friction at about 530 Hz in SUS 3105 stainless steel.
10' 30
' 3/-,
3'8
' 42
/.6
Tp -I / 10-L'K "I
FIG. 2 Relation between the vibrational frequency and the peak temperature.
Vol.
19, No. 1
INTERNAL FRICTION IN STAINLESS STEEL
49
fo = 2.4 x i0 II s -1, being consistent with the results of hydrogen diffusion in austenitic stainless steel (i0). The open circles and the solid circles are the present results for the hydrogen peak and the deuterium peak, respectively, lying in the temperature range from 293 K to 318 K. Although this temperature range was rather narrow, all the data points fall close to the previous Arrhenius line. It is seen in FIG.2 that the solid circles for deuterium are always shifted to the left, or to the higher temperature side than the open circles for hydrogen. Such isotope shifts suggest that the internal friction peak under discussion is a diffusion-related phenomenon, possibly supporting the previous assumption of a Snoek-type relaxation (2,3). Unfortunately, it is difficult to distinguish the Arrhenius relation for deuterium from that for hydrogen, because of the narrow temperature range in the present study. However, the ratio of the vibrational frequencies for hydrogen to deuterium, fH/fD, can be determined at each peak temperature by the method of interpolation. The obtained values of fH/fD seem to decrease with temperature but show considerable scatter. As a tentative measure, the average value may be useful over the temperature range from 293 K to 318 K; the statistical treatment leads to fH/fD = 1.31 ± 0.07 at the 90% confidence level. On the assumption of a Snoek-type relaxation, the vibrational frequency at the peak temperature should correspond to the diffusional jump frequency of hydrogen or deuterium atoms. Then the diffusion coefficient can be expressed as D = (2~d2/6~)f , as discussed previously (3). Here d is the distance of one diffusional jump and ~ is the geometrical factor for the diffusional path, both of which are considered to be the same for hydrogen and deuterium. Thus, it follows that DH/D D = fH/fD. It is therefore concluded that DH/D D = 1.31 ± 0.07
at 293-318 K.
This ratio is clearly larger than unity corresponding to the case of no isotope effect, but slightly smaller t h a n ~ corresponding to the value predicted by classical theory. For the 310-type austenitic also reported that
stainless
DH/D D = 1.38 ± 0.12
steel,
Quick and Johnson
(i0) have
at 472-716 K.
This is nearer to V ~ and somewhat larger than the value obtained in the present study. It is not clear at present whether this discrepancy results from the difference of temperature ranges or from the difference of experimental methods. For pure nickel (Ii) and its dilute alloys (12), the remarkable temperature dependence of DH/D D has been reported below 300 K down to 125 K, and discussed in terms of quantum mechanical tunnelling and anharmonic lattice oscillation. However, for higher nickel alloys including austenitic stainless steel, the temperature dependence of DH/D D has never been reported in the literature. Data at lower temperatures are especially required for higher nickel alloys as well. Conclusion The isotope effect of hydrogen diffusion in austenitic stainless steel was evaluated from the hydrogen peak and the deuterium peak of internal friction. The average isotope ratio of the diffusion coefficients was 1.31 ± 0.07 over the temperature range from 293 K to 318 K. This is slightly smaller than the value predicted by classical theory.
50
INTERNAL FRICTION IN STAINLESS STEEL
(I) (2) (3) (4) (5) (6) (7) (8) (9) (I0) (ii) (12) (13)
Vol. 19, No. I
References S.Asano, M.Goto and R.Otsuka: J . J a p a n I n s t . M e t . , 39, 1318 (1975). S.Asano, R.Tsunoda and R.Otsuka: J . J a p a n I n s t . M e t . , 41, 338 (1977). S.Asano, M.Shibata and R.Tsunoda: S c r i p t a M e t . , 14, 377 (1980). N . I g a t a , H.B.Chen and K.Miyahara: S c r i p t a Met . , 16, 169 (1982). S.Asano and K.Oshima: T r a n s . J a p a n I n s t . M e t , , 23, 530 (1982). R.R,Arons, J.Bouman, M.Wijzenbeek, P . T . A . K l a a s e , C.Tuyn, G . L e f e r i n k and G.De V r i e s : Acta M e t . , 15, 144 (1967). P.Vajda, J.N.Daou and P.Moser: J . P h y s i q u e , 44, 543 (1983). S.Asano and H.Seki: Scripta Met., 18, 117 (1984). H.Seki and S.Asano: J.Japan Inst.Met., 48, 694 (1984). N.R.Quick and H.H.Johnson: Met. Trans.A, i0, 67 (1979). K.Yamakawa: J.Phys.Soc. Japan, 47, 114 (1979). B.Hohler and H.Schreyer: J.Phys.F, 12, 857 (1982). K.Farrell and M.B.Lewis: Scripta Met., 15, 661 (1981).
A HYDROGEN
Vol. 19, pp. 47-50, 1985 Printed in the U.S.A.
Pergamon Press Ltd. All rights reserved
PEAK OF INTERNAL FRICTION AND ITS ISOTOPE EFFECT IN AUSTENITIC S. Asano
STAINLESS
and
STEEL
M. Kazaoka
Department of Metallurgical Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
(Received
September
12, 1984)
Introduction In austenitic stainless steels such as SUS 310S, SUS 316 and SUS 304, an internal friction peak due to dissolved hydrogen has been found at about 300 K by Asano et al.(l-3) and confirmed by Igata et al.(4). As has been reported in a previous paper (2), its peak height increases with the hydrogen concentration while its peak temperature remains constant. This internal friction peak is characterized by the same activation energy as that of hydrogen diffusion (3) but never affected by cold work (4,5). Although its mechanism is not known in detail, it has been attributed to a Snoek-type relaxation of hydrogen atom-pairs reorienting in the fcc Fe-Cr-Ni lattice (2, 3). This is analogous to the hydrogen peak of internal friction in fcc Pd-H (6), hcp Lu-H (7) and fcc Fe-Ni-H alloys (8,9). Such an internal friction peak may provide useful information on hydrogen diffusion. For a similar type of austenitic stainless steel, Quick and Johnson (i0) have made a precise measurement of hydrogen and deuterium diffusion over the temperature range from 472 K to 779 K. They have found an isotope effect; the ratio of the diffusion coefficients of hydrogen to deuterium, DH/DD, is near to ~-~-, which is the value predicted by classical theory. Meanwhile, in pure nickel (Ii) and its dilute alloys (12), the measured value of DH/D D is known to be temperature-dependent, deviating remarkably f r o m ~ at lower temperatures. It is therefore necessary to examine the isotope effect of hydrogen diffusion in austenitic stainless steel in the temperature range lower than that of Quick and Johnson. The purpose of this study is to detect hydrogen and deuterium peaks of internal friction in austenitic stainless steel and to determine the value of DH/D D at about 300 K on the assumption of a Snoek-type relaxation. The isotope effect will be revealed as the difference in the peak temperature between hydrogen and deuterium. Experimental
Procedure
The experimental conditions for deuterium were almost the same as those adopted previously for hydrogen (2,3). The material used was a commercial austenitic stainless steel designated as SUS 310S ( Fe-25%Cr-20%Ni ), which is known as a stable fcc alloy. It was machined into plate specimens in various sizes; 54-90 mm in length, 0.53-1.41 mm in thickness and i0 mm in width. All the specimens were solution-treated for one hour in vacuum at 1323 K and then quenched into iced water. The specimens were electrolytically charged with hydrogen at room temperature. The electrolytes used were IN H2SO4-H20
47 0036-9748/85 $3.00 + .00 Copyright (c) 1985 Pergamon Press Ltd.
and deuterium solution for
48
INTERNAL FRICTION IN STAINLESS STEEL
Vol. 19, No. I
hydrogen charging and IN D2SO4-D20 solution for deuterium charging, both of which were poisoned with 250 mg As20 3 per liter. The current density was 500 A/m 2 and the charging time was 20 hours. According to Farrell and Lewis (13), the concentration of hydrogen or deuterium might be 0.5-0.8 atoms per metal atom in the near-surface region before the measurement of internal friction. Internal friction was measured by the free decay method in transverse vibration in the temperature range from 160 K to 370 K at a heating rate of 0.017 K/s. The testing frequency varied from 300 Hz to 2300 Hz by changing the specimen size. Under these conditions, the peak temperatures are expected to lie within the range of 290-320 K. Results and Discussion FIG.I shows the internal friction peaks caused by hydrogen charging and by deuterium charging, which were measured at nearly equal frequencies. The height and position of the hydrogen peak were entirely consistent with the previous results (2,3). On the other hand, the deuterium peak had almost the same height but was apparently located at a temperature 4-5 K higher than the hydrogen peak. The difference in the peak temperature may result from an isotope effect between hydrogen and deuterium, as observed in palladium (6) and lutetium (7). It should be noted that the peak temperature does not depend on the hydrogen concentration (2,5), nor possibly on the deuterium concentration. FIG.2 shows the Arrhenius graph relating the reciprocals of peak temperatures to the logarithms of vibrational frequencies. The solid line in this figure is an Arrhenius relation for the hydrogen peak, which has been reported by Asano et al.(3) over the temperature range from 230 K to 310 K. This yields the activation energy E = 49.0 kJ/mol and the frequency factor Tp /
310 SUS310S 6
o Hydrogen •
1 0 '~
~'Oo,. oe
Deuterium
° e
oe
t~O
10 3
o.
8
°e
ARRHENIUS PLOT
*O
0 •
Hydrogen Deuterium
102
::
101
~%"
2
220 ,
o
~.
o
240 ,
N "r
oe
T
K
260 ,
° oe
°e
"-4
,
,~
°e
°e
280 ,
o ~" ~oooOe~%~ •
0 150
I
200
I
1
a
250 300 350 400 T / K FIG. 1 Hydrogen and deuterium peaks of internal friction at about 530 Hz in SUS 3105 stainless steel.
10' 30
' 3/-,
3'8
' 42
/.6
Tp -I / 10-L'K "I
FIG. 2 Relation between the vibrational frequency and the peak temperature.
Vol.
19, No. 1
INTERNAL FRICTION IN STAINLESS STEEL
49
fo = 2.4 x i0 II s -1, being consistent with the results of hydrogen diffusion in austenitic stainless steel (i0). The open circles and the solid circles are the present results for the hydrogen peak and the deuterium peak, respectively, lying in the temperature range from 293 K to 318 K. Although this temperature range was rather narrow, all the data points fall close to the previous Arrhenius line. It is seen in FIG.2 that the solid circles for deuterium are always shifted to the left, or to the higher temperature side than the open circles for hydrogen. Such isotope shifts suggest that the internal friction peak under discussion is a diffusion-related phenomenon, possibly supporting the previous assumption of a Snoek-type relaxation (2,3). Unfortunately, it is difficult to distinguish the Arrhenius relation for deuterium from that for hydrogen, because of the narrow temperature range in the present study. However, the ratio of the vibrational frequencies for hydrogen to deuterium, fH/fD, can be determined at each peak temperature by the method of interpolation. The obtained values of fH/fD seem to decrease with temperature but show considerable scatter. As a tentative measure, the average value may be useful over the temperature range from 293 K to 318 K; the statistical treatment leads to fH/fD = 1.31 ± 0.07 at the 90% confidence level. On the assumption of a Snoek-type relaxation, the vibrational frequency at the peak temperature should correspond to the diffusional jump frequency of hydrogen or deuterium atoms. Then the diffusion coefficient can be expressed as D = (2~d2/6~)f , as discussed previously (3). Here d is the distance of one diffusional jump and ~ is the geometrical factor for the diffusional path, both of which are considered to be the same for hydrogen and deuterium. Thus, it follows that DH/D D = fH/fD. It is therefore concluded that DH/D D = 1.31 ± 0.07
at 293-318 K.
This ratio is clearly larger than unity corresponding to the case of no isotope effect, but slightly smaller t h a n ~ corresponding to the value predicted by classical theory. For the 310-type austenitic also reported that
stainless
DH/D D = 1.38 ± 0.12
steel,
Quick and Johnson
(i0) have
at 472-716 K.
This is nearer to V ~ and somewhat larger than the value obtained in the present study. It is not clear at present whether this discrepancy results from the difference of temperature ranges or from the difference of experimental methods. For pure nickel (Ii) and its dilute alloys (12), the remarkable temperature dependence of DH/D D has been reported below 300 K down to 125 K, and discussed in terms of quantum mechanical tunnelling and anharmonic lattice oscillation. However, for higher nickel alloys including austenitic stainless steel, the temperature dependence of DH/D D has never been reported in the literature. Data at lower temperatures are especially required for higher nickel alloys as well. Conclusion The isotope effect of hydrogen diffusion in austenitic stainless steel was evaluated from the hydrogen peak and the deuterium peak of internal friction. The average isotope ratio of the diffusion coefficients was 1.31 ± 0.07 over the temperature range from 293 K to 318 K. This is slightly smaller than the value predicted by classical theory.
50
INTERNAL FRICTION IN STAINLESS STEEL
(I) (2) (3) (4) (5) (6) (7) (8) (9) (I0) (ii) (12) (13)
Vol. 19, No. I
References S.Asano, M.Goto and R.Otsuka: J . J a p a n I n s t . M e t . , 39, 1318 (1975). S.Asano, R.Tsunoda and R.Otsuka: J . J a p a n I n s t . M e t . , 41, 338 (1977). S.Asano, M.Shibata and R.Tsunoda: S c r i p t a M e t . , 14, 377 (1980). N . I g a t a , H.B.Chen and K.Miyahara: S c r i p t a Met . , 16, 169 (1982). S.Asano and K.Oshima: T r a n s . J a p a n I n s t . M e t , , 23, 530 (1982). R.R,Arons, J.Bouman, M.Wijzenbeek, P . T . A . K l a a s e , C.Tuyn, G . L e f e r i n k and G.De V r i e s : Acta M e t . , 15, 144 (1967). P.Vajda, J.N.Daou and P.Moser: J . P h y s i q u e , 44, 543 (1983). S.Asano and H.Seki: Scripta Met., 18, 117 (1984). H.Seki and S.Asano: J.Japan Inst.Met., 48, 694 (1984). N.R.Quick and H.H.Johnson: Met. Trans.A, i0, 67 (1979). K.Yamakawa: J.Phys.Soc. Japan, 47, 114 (1979). B.Hohler and H.Schreyer: J.Phys.F, 12, 857 (1982). K.Farrell and M.B.Lewis: Scripta Met., 15, 661 (1981).