Tensile fracture behavior of AA7075 alloy produced by thixocasting


KILIÇLI V. , AKAR N., ERDOĞAN M. , KOCATEPE K.

TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA, vol.26, no.5, pp.1222-1231, 2016 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 26 Issue: 5
  • Publication Date: 2016
  • Doi Number: 10.1016/s1003-6326(16)64223-1
  • Title of Journal : TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
  • Page Numbers: pp.1222-1231

Abstract

Tensile fracture behaviors of thixocast, artificially aged thixocast (thixocast+T6) and as-extruded AA7075 alloys were investigated. The microstructural and fractographic observations were carried out using optical microscope (OM) and scanning electron microscope (SEM). Experimental studies showed that as-extruded and thixocast+T6 specimens exhibited considerably more excellent mechanical properties than as-thixocast AA7075 specimen. T6 artificial heat treatment with prolonged solution treatment significantly improved the tensile properties of the thixocast AA7075 alloy. The tensile properties of as-extruded and thixocast+T6 specimens were close to each other. In as-thixocast specimen having remarkable micro-cracks, fracture was intergranular brittle type. The ductile fracture surfaces were observed in as-extruded and thixocast+T6 specimens. In as-thixocast specimens, decohesion started between the eutectic-matrix interfaces and propagated through grains. Micro-void coalescence was the dominant form of fracture in thixocast+T6 heat treated specimens. The micro-voids nucleation was initiated at the interface between the matrix and multinary eutectic structure.