| dc.contributor.author | Lenartová, I. | |
| dc.contributor.author | Galland, J. | |
| dc.contributor.author | Tvrdý, Miroslav | |
| dc.contributor.author | Vodárek, Vlastimil | |
| dc.contributor.author | Hyspecká, Ludmila | |
| dc.date.accessioned | 2007-08-10T10:46:04Z | |
| dc.date.available | 2007-08-10T10:46:04Z | |
| dc.date.issued | 1999 | |
| dc.identifier.citation | Revue de Métallurgie: Cahiers d'Informations Techniques. 1999, vol. 96, no 2, p. 243-251. | en |
| dc.identifier.issn | 0035-1563 | |
| dc.identifier.issn | 1156-3141 | |
| dc.identifier.uri | http://hdl.handle.net/10084/61715 | |
| dc.description.abstract | Les propriétés mécaniques des alliages austénitiques peuvent être fortement modifiées en présence d'une hydrogénation. Cette étude a pour objectif de préciser cette influence sur deux alliages (800 et 600) pour lesquels la composition chimique, d'une part, et la microstructure, d'autre part, présentent des différences significatives. L'hydrogénation a été réalisée préalablement à la traction, sous polarisation cathodique potentiostatique à 300°C, pendant des durées comprises entre 5 et 48 h. Une forte fragilisation par l'hydrogène a été mise en évidence dans le cas de l'alliage 600 à l'état hypertrempé et revenu avec précipités aux joints de grains; elle est plus faible à l'état hypertrempé sans précipités aux joints de grains. En revanche, l'alliage 800 n'est pas fragilisé par l'hydrogène, ni à l'état hypertrempé ni à l'état hypertrempé et revenu, même en présence de précipités. L'influence d'une ségrégation du phosphore sur les joints de grains peut expliquer les différences observées. | en |
| dc.language.iso | fr | en |
| dc.publisher | Revue de Métallurgie | en |
| dc.relation.ispartofseries | Revue de Métallurgie: Cahiers d'Informations Techniques | en |
| dc.relation.uri | https://doi.org/10.1051/metal/199996020243 | |
| dc.title | Fragilisation par l'hydrogène d'alliages austénitiques : rôle de la microstructure et de la ségrégation des impuretés soufre et phosphore | en |
| dc.title.alternative | Hydrogen embrittlement for austenitic alloys: behaviour of microstructure and segregation of sulphur and phosphorus impurities | en |
| dc.type | article | en |
| dc.identifier.location | Ve fondu ÚK | en |
| dc.description.abstract-en | The mechanical properties of the austenitic alloys generally depend on their chemical composition and microstructure, but they can be significantly modified by the presence of hydrogen. In this paper, the effect of hydrogen on two nickel (800 and 600) alloys has been investigated for different composition and microstructure.
The alloy 800 has been studied in three structural states : A (as received condition) and Al, A2, representing two different heat treatments. The alloy 600 has been investigated in as received condition (B) and after heat treatment (B1).
The state A of alloy 800 was represented by the austenitic microstructure with the presence of M23C6 carbides in the matrix, nevertheless the grain boundaries remained clean. Further, the carbides and carbonitrides of Ti, as well as the carbosulfides of titanium (Ti4C2S2) are detected in the intragranular space. The heat treatment designated Al was represented by the annealing treatment for la h at 700 degrees C, whereas the heat treatment designated A2 consisted of the solution treatment for 20 min at 1000 degrees C followed by annealing for 50 h at 700 degrees C. Both treatments A I and A2 have been employed to provoke the continuous precipitation of the carbides M23C6 at the grain boundaries.
The microstructure of the alloy 600 in the as delivered condition (B) was formed by the austenite with the precipitation of the carbides M23C6 on the austenitic grain boundaries. The same carbides were present in the matrix but were of the acicular morfology. The next heat treatment BI which consisted of the solution treatment for 20 min at 1050 degrees C produced the net austenitic microstructure with all the carbides diluted in the solid solution.
The effect of the microstructure on the mechanical behaviour of both alloys at the presence and the absence of hydrogen has been studied by means of the tensile test at ambient temperature. The hydrogen charging was realized before the mechanical testing by the potentiostatic cathodic polarization of the specimens, by the electrolysis of the water injected into the salt bath at the temperature of 300 degrees C for the time intervals from 5 to 48 h.
To study the microsegregation behaviour of both alloy and impurity (phosphorus and sulphur) elements on the grain boundaries the free surface segregation has been monitored on the samples of alloys in the broad range of annealing temperatures. The procedure consisted of the stepwise annealing of the samples at increasing temperatures and each anneal was followed by the measurement of the Auger electron spectra at the temperature lower than 300 degrees C and subsequent ion etching of the segregated layer.
The most intensive hydrogen embrittlement has been observed in case of solution treated and sensitized alloy 600 with significant precipitation of carbides on the grain boundaries, the fractures being of the fully intergranular brittle nature. The solution treated state of the same alloy demonstrated less embrittlement and less intergranularity of fractures. On the contrary, the alloy 800 has been resistant to the hydrogen embrittlement, both in the solution treated and sensitized conditions. The observed differences have been explained by the different picture of phosphorus free surface segregation as measured by the Auger spectrometry. | en |
| dc.identifier.doi | 10.1051/metal/199996020243 | |
| dc.identifier.wos | 000079793500012 | |