Consequences of a Room-Temperature Plastic Deformation During Processing on Creep Durability of a Ni-Based SX Superalloy
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Consequences of a Room-Temperature Plastic Deformation During Processing on Creep Durability of a Ni-Based SX Superalloy SARAH HAMADI, FLORENCE HAMON, JOE¨L DELAUTRE, JONATHAN CORMIER, PATRICK VILLECHAISE, SATOSHI UTADA, PARASKEVAS KONTIS, and NATHALIE BOZZOLO Ni-based single crystalline superalloys are used for high-pressure parts of aero-engines due to their superior mechanical properties and very good oxidation resistance at high temperature. However, shocks or unexpected mismatch in thermal contraction between molds and castings can occur during casting process and subsequent heat treatments, inducing plastic deformation of the alloy at low temperature. To mimic such events, a tensile plastic deformation is applied at room temperature on solutioned AM1 specimens and followed by standard aging heat treatments. Faster growth of the c¢ precipitates inside plastically deformed bands is obtained after full heat treatment with no lattice rotation or recrystallization. It has however been evidenced that the applied deformation has a detrimental impact on the creep properties, especially at high temperature (above 950 C). It partly results from a highly localized failure process along former slip bands in which recrystallization is observed. The evolution of the microstructure during creep tests of prior deformed and nondeformed specimens has been thoroughly investigated to better identify under which conditions recrystallization occurs inside the bands during a creep test and by which mechanism. https://doi.org/10.1007/s11661-018-4748-3 The Minerals, Metals & Materials Society and ASM International 2018
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INTRODUCTION
NI-BASED single crystalline (SX) superalloys are widely used for blades and vanes of the hottest sections of land-based gas turbines and aero-engines due to their superior mechanical properties and very good oxidation resistance.[1,2] Heat treatments applied to these alloys generally comprise a solution heat treatment followed by two (or more) aging heat treatments. Their main aims
SARAH HAMADI and JOE¨L DELAUTRE are with Safran Aircraft Engines, Site de Villaroche, Rond-Point Rene´ Ravaud - Re´au, 77550 Moissy-Cramayel, France. Contact e-mail: [email protected] FLORENCE HAMON, JONATHAN CORMIER and PATRICK VILLECHAISE are with the Institut Pprime, UPR CNRS 3346, Physics and Mechanics of Materials Department, ISAE-ENSMA, BP 40109, 86961 FuturoscopeChasseneuil Cedex, France. SATOSHI UTADA is with Safran Aircraft Engines and also with the Institut Pprime, UPR CNRS 3346, Physics and Mechanics of Materials Department, ISAEENSMA. PARASKEVAS KONTIS is with the Max-Planck-Institut fu¨r Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Du¨sseldorf, Germany. NATHALIE BOZZOLO is with the MINES ParisTech, PSL Research University, CEMEF - Centre de mise en forme des mate´riaux, CNRS UMR 7635, CS 10207, rue Claude Daunesse 06904 Sophia Antipolis Cedex, France. Manuscript submitted March 9, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
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