Microstructure mapping in friction stir welds of 7449 aluminium alloy using SAXS.

M. Dumont (1) , A. Steuwer (2) , A. Deschamps (3) , M. Peel (2) , Philip Withers (2)

1 TECSEN - Laboratoire de thermodynamique, propriétés électriques, contraintes, structures aux échelles nanométriques
2 University of Manchester [Manchester]
3 LTPCM - Laboratoire de thermodynamique et physico-chimie métallurgiques

This paper describes the microstructural response of an age-hardenable, high-strength 7449 aluminium alloy to friction stir welding. Plates in the naturally aged (T3) and over-aged (T79) conditions were welded using two weld tool translation speeds. Maps of precipitate volume fraction and size were obtained by spatially resolved small-angle X-ray scattering over a cross-section of the welded plate, complemented by direct observations made by transmission electron microscopy. The spatial variations of precipitate volume fraction and size were assessed quantitatively for the characteristic zones of the welds, and supported by complementary hardness measurements. The effect of initial microstructure and welding speed, in particular in the heat-affected and thermomechanically affected zones, is discussed.

Mots clés: Microstructure; Precipitation; 7xxx alloys; Small-angle X-ray scattering; Synchrotron X-rays

Domaines: Matériaux; Génie des procédés

M. Dumont, A. Steuwer, A. Deschamps, M. Peel, Philip Withers. Microstructure mapping in friction stir welds of 7449 aluminium alloy using SAXS.. Acta Materialia, 2006, 54 (18), pp.4793-4801. ⟨10.1016/j.actamat.2006.06.015⟩. ⟨hal-00139872⟩