Effect of surface defects on the fatigue behavior of a cast TiAl alloy.

2000 ◽  
Vol 646 ◽  
Author(s):  
M. Nazmy ◽  
M. Staubli ◽  
G. Onofrio ◽  
V. Lupinc
Keyword(s):  
Tial Alloy ◽  
High Cycle Fatigue ◽  
Surface Defects ◽  
Fatigue Behavior ◽  
Impact Resistance ◽  
Economic Life ◽  
Crack Advance ◽  
Crack Growth Behavior ◽  
Engine Components ◽  
Effect Of Surface

ABSTRACTThe effect of surface defects on the performance of TiAl-base alloys is an issue of importance in contemplating their application into engine components. Due to the relatively low ductility and low impact resistance of gamma alloys the validation of models for estimating economic life and for safe-life approaches employed for components becomes of great importance. Surface defects can be attributed to various sources during the manufacturing or handling of the components. In fact, little is known about the detrimental effects of surface defects on gamma alloys. In the present study, the effect of artificially introduced surface defects, on the high cycle fatigue behavior of the Ti-47Al-2W-0.5Si, will be investigated and correlated with the crack growth behavior at 700°C. The results are reported in the form of the Kitagawa diagram in which the safe and unsafe zones for crack advance and fracture are defined.

Effect of the Rheocasting Process and of the SLS Layer on the Fatigue Behavior of 357 Aluminum Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 227-234 ◽  
Author(s):  
Alain Abou Antoun ◽  
Myriam Brochu ◽  
Heinrich Möller
Keyword(s):  
Aluminum Alloy ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Initiation Mechanism ◽  
Liquid Segregation ◽  
Surface Liquid ◽  
Effect Of Surface

Two objectives were targeted: 1) compare the high cycle fatigue behavior of rheocast aluminum alloy 357 prepared by the swirl enthalpy equilibration device (SEED) and by the Council for Scientific and Industrial Research (CSIR) process, and 2) study the effect of surface liquid segregation (SLS) on the fatigue behavior of the CSIR material. Rectangular hourglass specimens machined from rheocast plates were tested at four stress amplitudes in axial fatigue with a stress ratio of R = -1 and a frequency of 20 Hz. Results obtained for SLS free specimens show that the SEED and the CSIR processes produce rheocast materials with comparable high cycle fatigue properties, 115 MPa at 107 cycles. In order to study the influence of surface liquid segregation, slightly polished specimens with a remaining SLS of nearly 750 microns thick were also tested. According to the results, the SLS reduces the average fatigue strength by approximately 5% (110 MPa vs. 115 MPa at 107 cycles). For SLS free specimens, the fatigue crack initiated at shrinkage cavities, oxide films or in the alpha globules. On the other hand, for specimens with SLS, no crack initiation in the alpha globules was observed. The main crack initiation mechanism was identified to be a deformation incompatibility between regions characterized by higher silicon content compared to nominal eutectic regions. The originality of the work is provided by the rigorous comparative analysis of the fatigue performance of components produced in two different rheocasting facilities, but tested in a single laboratory. It is also the first fundamental research published on the mechanical effect of surface liquid segregation. It confirms that SLS should be removed in critical areas in order to optimize the fatigue resistance of rheocast components.

scholarly journals Influence of warm caliber rolling on tensile response and high cycle fatigue behavior of hypereutectoid steel

2021 ◽  
Vol 10 ◽  
pp. 205-215
Author(s):  
Kyu-Sik Kim ◽  
Young-Kyun Kim ◽  
Hyeon-Jin Kim ◽  
Jeoung Han Kim ◽  
Kee-Ahn Lee
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Hypereutectoid Steel ◽  
Tensile Response
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