Effects of thermal cycling and microstructure on the fatigue crack propagation in forged titanium–aluminide alloys under thermomechanical fatigue conditions

2020 ◽  
Vol 797 ◽  
pp. 140248
Author(s):  
Yasuhiro Yamazaki ◽  
Ryota Sugaya ◽  
Ukyo Kobayashi ◽  
Yutaro Ohta
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Thermal Cycling ◽  
Fatigue Crack Propagation ◽  
Titanium Aluminide ◽  
Thermomechanical Fatigue ◽  
Titanium Aluminide Alloys

scholarly journals Effect of microstructure on fatigue crack propagation in a titanium-aluminide alloy under thermomechanical fatigue conditions - Current activities in the subcommittee of Titanium-Aluminide alloys in the Society of Materials Science, Japan (JSMS) -

2020 ◽  
Vol 321 ◽  
pp. 11055
Author(s):  
Yasuhiro Yamazaki ◽  
Ryota Sugaya ◽  
Fumio Tooyama
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Titanium Aluminide ◽  
Collaborative Research ◽  
High Temperature Strength ◽  
Tial Alloys ◽  
Titanium Aluminide Alloys ◽  
Effect Of Microstructure

Titanium aluminide (TiAl) alloys have attracted to considerable interest as a material of blade in the low-pressure turbine section of aero engines since their superior specific strength. The mechanical properties and strengths of TiAl alloys are strongly sensitive to their microstructure controlled with thermo-mechanical processing. The collaborative research has been started from 2017 by the subcommittee on Titanium-Aluminide alloys, JSMS Committee on High Temperature Strength of Materials, in order to get basic information about the influence of microstructure on the high-temperature strength. This paper is a part of the collaborative research. The crack propagation tests were carried out under the load controlled out-of-phase type TMF (OP-TMF) loading condition with temperature range 400 ℃ -760 ℃ . The effect of microstructure on fatigue crack propagation behavior in was discussed.

Fatigue-Crack Propagation in Gamma-Based Titanium Aluminide Alloys at Large and Small Crack Sizes

1998 ◽  
Vol 552 ◽  
Author(s):  
J. J Kruzic ◽  
J. P Campbell ◽  
R. O. Ritchie
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Titanium Aluminide ◽  
Lamellar Microstructure ◽  
Small Crack ◽  
Fatigue Crack Growth Resistance ◽  
Average Grain Size ◽  
Titanium Aluminide Alloys

ABSTRACTMost evaluations of the fracture and fatigue-crack propagation properties of γ + α2 titanium aluminide alloys to date have been performed using standard "large-crack" samples, e.g., compact-tension specimens containing crack sizes which are on the order of tens of millimeters, i.e., large compared to microstructural dimensions. However, these alloys have been targeted for applications, such as blades in gas-turbine engines, where relevant crack sizes are much smaller (<500 µm) and where the small-crack fatigue threshold may be the most relevant design parameter. In this study, we compare and contrast the cyclic crack-growth behavior of both large (a > 5 mm) and small (c ∼ 25–300 µm) cracks in a γ-TiAl based alloy, of composition Ti-47A1–2Nb-2Cr-0.2B (at%), specifically for duplex (average grain size ∼17 µm) and refined lamellar (average colony size ∼150 µm) microstructures. It is found that, whereas the lamellar microstructure displays far superior fracture toughness and fatigue-crack growth resistance in the presence of large cracks, in small-crack testing the duplex microstructure exhibits a better combination of properties. The reasons for such contrasting behavior are examined in terms of the intrinsic and extrinsic (i.e., crack bridging) contributions to cyclic crack advance.

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