Microstructural features controlling the variability in low-cycle fatigue properties of alloy Inconel 718DA at intermediate temperature - Archive ouverte HAL
Journal Articles Metallurgical and Materials Transactions A Year : 2016

Microstructural features controlling the variability in low-cycle fatigue properties of alloy Inconel 718DA at intermediate temperature

Abstract

The low-cycle fatigue behavior of two direct-aged versions of the nickel-based superalloy Inconel 718 (IN718DA) was examined in the low-strain amplitude regime at intermediate temperature. High variability in fatigue life was observed, and abnormally short lifetimes were systematically observed to be due to crack initiation at (sub)-surface non-metallic inclusions. However, crack initiation within (sub)-surface non-metallic inclusions did not necessarily lead to short fatigue life. The macro- to micro-mechanical mechanisms of deformation and damage have been examined by means of detailed microstructural characterization, tensile and fatigue mechanical tests, and in situ tensile testing. The initial stages of crack micro-propagation from cracked non-metallic particles into the surrounding metallic matrix occupies a large fraction of the fatigue life and requires extensive local plastic straining in the matrix adjacent to the cracked inclusions. Differences in microstructure that influence local plastic straining, i.e., the δ-phase content and the grain size, coupled with the presence of non-metallic inclusions at the high end of the size distribution contribute strongly to the fatigue life variability.
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Dates and versions

hal-01644848 , version 1 (13-12-2017)

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Damien Texier, Ana Casanova Gómez, Stéphane Pierret, Jean-Michel Franchet, Tresa M. Pollock, et al.. Microstructural features controlling the variability in low-cycle fatigue properties of alloy Inconel 718DA at intermediate temperature. Metallurgical and Materials Transactions A, 2016, 47 (3), pp.1096 - 1109. ⟨10.1007/s11661-015-3291-8⟩. ⟨hal-01644848⟩
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