Details
| Original language | English |
|---|---|
| Pages (from-to) | 1413-1425 |
| Number of pages | 13 |
| Journal | International journal of fatigue |
| Volume | 29 |
| Issue number | 8 |
| Publication status | Published - Aug 2007 |
| Externally published | Yes |
Abstract
The present study provides a survey on in situ fatigue devices suitable for loading specimens in a scanning electron microscope (SEM). Particular emphasis is placed on the experimental methods employed to operate a small-scale load frame in an environmental SEM (ESEM). Specimen design and surface preparation, various modes of conducting the fatigue tests, specimen heating and imaging at elevated temperatures are considered. In addition, recent data from in situ fatigue studies conducted in an ESEM between room temperature and 600 °C are summarized. Fatigue tests conducted on AM60B cast magnesium demonstrate a substantial environmental effect on cyclic deformation and fatigue damage evolution even at room temperature. Fatigue behaviour of high-temperature titanium alloy IMI 834 at 400 °C illustrates a completely different effect of environment on slip band formation and crack nucleation as compared to AM60B. Investigations performed on IMI 834 at 600 °C reveal current limitations of the in situ fatigue technique applied. An approach to overcome these limitations is discussed. Ambient conditions can be simulated in an ESEM using pure water vapour atmosphere at a pressure similar to the partial pressure of the ambient environment. This is demonstrated for AM60B at room temperature and IMI 834 at 400 °C. However, this approach cannot necessarily be applied to all other material/environment combinations as is exemplarily shown for in situ fatigue loading of IMI 834 at 600 °C. Data obtained from in situ fatigue testing are compared to those from post-mortem SEM studies of failed specimens, which portray a wrong impression in certain cases. Experimental issues specific to environmental in situ testing at elevated temperatures are addressed as are the ramifications of such tests with respect to modelling of fatigue life.
Keywords
- AM60B, Cast magnesium, Crack initiation, Damage evolution, Environmental degradation, Fatigue mechanisms, High-temperature titanium alloy, IMI 834, In situ fatigue, Microstructure, Small crack growth
ASJC Scopus subject areas
- Mathematics(all)
- Modelling and Simulation
- Materials Science(all)
- General Materials Science
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
- Engineering(all)
- Industrial and Manufacturing Engineering
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In: International journal of fatigue, Vol. 29, No. 8, 08.2007, p. 1413-1425.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - In-situ fatigue in an environmental scanning electron microscope - Potential and current limitations
AU - Biallas, G.
AU - Maier, H. J.
N1 - Funding Information: Financial support by Deutsche Forschungsgemeinschaft is gratefully acknowledged.
PY - 2007/8
Y1 - 2007/8
N2 - The present study provides a survey on in situ fatigue devices suitable for loading specimens in a scanning electron microscope (SEM). Particular emphasis is placed on the experimental methods employed to operate a small-scale load frame in an environmental SEM (ESEM). Specimen design and surface preparation, various modes of conducting the fatigue tests, specimen heating and imaging at elevated temperatures are considered. In addition, recent data from in situ fatigue studies conducted in an ESEM between room temperature and 600 °C are summarized. Fatigue tests conducted on AM60B cast magnesium demonstrate a substantial environmental effect on cyclic deformation and fatigue damage evolution even at room temperature. Fatigue behaviour of high-temperature titanium alloy IMI 834 at 400 °C illustrates a completely different effect of environment on slip band formation and crack nucleation as compared to AM60B. Investigations performed on IMI 834 at 600 °C reveal current limitations of the in situ fatigue technique applied. An approach to overcome these limitations is discussed. Ambient conditions can be simulated in an ESEM using pure water vapour atmosphere at a pressure similar to the partial pressure of the ambient environment. This is demonstrated for AM60B at room temperature and IMI 834 at 400 °C. However, this approach cannot necessarily be applied to all other material/environment combinations as is exemplarily shown for in situ fatigue loading of IMI 834 at 600 °C. Data obtained from in situ fatigue testing are compared to those from post-mortem SEM studies of failed specimens, which portray a wrong impression in certain cases. Experimental issues specific to environmental in situ testing at elevated temperatures are addressed as are the ramifications of such tests with respect to modelling of fatigue life.
AB - The present study provides a survey on in situ fatigue devices suitable for loading specimens in a scanning electron microscope (SEM). Particular emphasis is placed on the experimental methods employed to operate a small-scale load frame in an environmental SEM (ESEM). Specimen design and surface preparation, various modes of conducting the fatigue tests, specimen heating and imaging at elevated temperatures are considered. In addition, recent data from in situ fatigue studies conducted in an ESEM between room temperature and 600 °C are summarized. Fatigue tests conducted on AM60B cast magnesium demonstrate a substantial environmental effect on cyclic deformation and fatigue damage evolution even at room temperature. Fatigue behaviour of high-temperature titanium alloy IMI 834 at 400 °C illustrates a completely different effect of environment on slip band formation and crack nucleation as compared to AM60B. Investigations performed on IMI 834 at 600 °C reveal current limitations of the in situ fatigue technique applied. An approach to overcome these limitations is discussed. Ambient conditions can be simulated in an ESEM using pure water vapour atmosphere at a pressure similar to the partial pressure of the ambient environment. This is demonstrated for AM60B at room temperature and IMI 834 at 400 °C. However, this approach cannot necessarily be applied to all other material/environment combinations as is exemplarily shown for in situ fatigue loading of IMI 834 at 600 °C. Data obtained from in situ fatigue testing are compared to those from post-mortem SEM studies of failed specimens, which portray a wrong impression in certain cases. Experimental issues specific to environmental in situ testing at elevated temperatures are addressed as are the ramifications of such tests with respect to modelling of fatigue life.
KW - AM60B
KW - Cast magnesium
KW - Crack initiation
KW - Damage evolution
KW - Environmental degradation
KW - Fatigue mechanisms
KW - High-temperature titanium alloy
KW - IMI 834
KW - In situ fatigue
KW - Microstructure
KW - Small crack growth
UR - http://www.scopus.com/inward/record.url?scp=33947653270&partnerID=8YFLogxK
U2 - 10.1016/j.ijfatigue.2006.11.008
DO - 10.1016/j.ijfatigue.2006.11.008
M3 - Article
AN - SCOPUS:33947653270
VL - 29
SP - 1413
EP - 1425
JO - International journal of fatigue
JF - International journal of fatigue
SN - 0142-1123
IS - 8
ER -