Hold time effects on the crack growth behavior in Inco 718 alloy

Stéphane Pierret (1) , Raul de Moura Pinho (1) , André Pineau (2)

1 SNECMA Villaroche [Moissy-Cramayel]
2 CDM - Centre des Matériaux

The understanding o f hold time effects on the fatigue crack growth rate (FCGR) behavior above 500°C in Inco718 DA is a great challenge to develop an efficient model for predicting crack propagation life. Trapezoidal wave shape signal fatigue tests from 500°C to 650°C with hold times up to 3600 s were carried out on a small grain size (5-15 |im) alloy. FCGRs were measured using potential drop technique. SEM observations were carried out to correlate the measured FCGRs with the trans-or inter-granular aspect of the fatigue fracture surfaces. Using equations developed in the frame of the Local Approach of Fracture (LAF) theory, predicted life and crack growth rates are compared to experimental results. The emphasis is laid on time dependent effects, in particular those associated with oxidation.

Mots clés: Inconel718; hold time effect; high temperature fatigue; intergranular fracture

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Stéphane Pierret, Raul de Moura Pinho, André Pineau. Hold time effects on the crack growth behavior in Inco 718 alloy. 8th International symposium on superalloy 718 and derivatives, Sep 2014, Pittsburgh, United States. pp.537-551, ⟨10.1002/9781119016854.ch42⟩. ⟨hal-01113531⟩