Fatigue crack growth under large scale yielding condition in a cast automotive aluminum alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:743

Article

Dezecot, Sebastien^1,2,3  Rambaudon, Matthieu²  Koster, Alain²  Szmytka, Fabien^3,4  Maurel, Vincent²  Buffiere, Jean-Yves¹ 

[1] CNRS, INSA Lyon, MATEIS, UMR 5510, F-69621 Villeurbanne, France

[2] PSL Res Univ, CNRS, MINES ParisTech, MAT Ctr Mat,UMR 7633, BP 87, F-91003 Evry, France

[3] Grp PSA, Direct Rech & Innovat Automobile, Route Gisy, F-78943 Velizy Villacoublay, France

[4] ENSTA ParisTech, IMSIA, Chemin Huniere, F-91761 Palaiseau, France

关键词: Low Cycle Fatigue;    Cast aluminum alloy;    Fatigue crack growth;    Large scale yielding;    High temperature;   

DOI  :  10.1016/j.msea.2018.03.008

来源: Elsevier

【 摘 要 】

Low Cycle Fatigue crack growth tests have been performed at 250 degrees C in order to study fatigue crack growth under large scale yielding conditions in a material widely used at high temperature by the automotive industry for cylinder head applications. The studied material was a cast aluminum alloy AlSi7Cu3Mg (close to A319) produced by Lost Foam Casting. Two different microstructures were investigated: one containing large natural pores and another where pores have been removed by Hot Isostatic Pressing (HIP). Fatigue Crack Growth Rates (FCGR) have been measured by in situ surface optical microscopy for different loading conditions all inducing generalized plasticity and compared to assess the influence of pores on the FCGR. In situ observations coupled to post mortem analysis revealed strong crack interactions with both pores and large hard particles on specimen surfaces and in the bulk. FCGR ranging between 10(-6) and 10(-4) m/cycle appear to be mainly sensitive to applied strain amplitudes. Although pores promoted secondary crack initiations and crack coalescences, they seemed to have a limited effect on steady-state FCGR which has been analytically modeled using energy densities.

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