Effect of notches on high temperature fatigue/creep behaviour of CMSX-4 single crystals

0177709 - UFM-A 20013214 RIV SIGLE FR eng C - Konferenční příspěvek (zahraniční konf.)
Lukáš, Petr - Preclík, Pavel - Kunz, Ludvík - Čadek, Josef - Svoboda, Milan
Effect of notches on high temperature fatigue/creep behaviour of CMSX-4 single crystals.
Temperature-Fatigue Interaction. Paris: Société Francaise de Métallurgie et de Matériaux, 2001, s. 37-46.
[International Spring Meeting /9./. Paris (FR), 29.05.2001-31.05.2001]
Grant CEP: GA AV ČR IAA2041002; GA AV ČR KSK1010104
Výzkumný záměr: CEZ:AV0Z2041904
Klíčová slova: superalloy single crystals * notches * Monkman-Grant relationship
Kód oboru RIV: JL - Únava materiálu a lomová mechanika

Effect of notches on high temperature fatigue/creep strength of CMSX-4 single crystals has been investigated. Cylindrical bars of the orientation 001 with circumferential notches were tested at 850 °C under constant loads both without and with superimposed high frequency cyclic loads. Under creep conditions, the notched specimens exhibit a longer creep lifetime than the smooth specimens for the same net-section stress. Stress-strain analysis of the notched specimens subjected to constant loads was performed by an elastic-plastic FEM procedure; the experimentally determined creep data of smooth specimens were used as input data. An excellent correlation was found between the creep lifetime of the notched specimens and the average value of the calculated steady-state creep strain rate. The creep life curves of notched specimens were found to be identical with the creep life curves of smooth specimens when expressed in terms of Monkman-Grant diagram. Cyclic load components superimposed on static load reduce the time to failure. This reduction increases with increasing stress amplitude. Moreover, the mode of failure is changed from the ductile creep mode to the sharply localised fatigue mode.
Trvalý link: http://hdl.handle.net/11104/0074628