Effect of Friction Stir Processing on Microstructure and Mechanical Properties of a HPDC Magnesium Alloy

Abstract:

A high pressure die cast (HPDC) magnesium alloy was friction stir processed (FSP) at high rotation rates with different advancing speeds. The AZ91 plate was 3 mm thick and the pin had a truncated cone tip. The friction stir processing induced the disappearance of porosity (typical of the HPDC process) in the nugget zone but some tunnel defects were introduced. The presence of characteristic FSP zones is not obvious due to the low plastic deformation of this alloy. The stirred zone is very narrow around the tool and this makes the FSP difficult to occur in the whole thickness of the plate. Microhardness values and electrical conductivity are sensitive to stirred zone and differences arise according to FSP parameters. The grain size is refined and homogenized by FSP due to partial solubilisation and disappearance of the eutectic phase surrounding Mg-alpha. X-rays diffractometry was performed on FSP samples to index phases and calculate peak shifts of Mg-alpha.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 1735-1740
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.1735
• Online since: May 2014
• Authors: Emanuela Cerri*, Paola Leo
• Keywords: AZ91HPDC, FSP, Microhardness, Microstructure

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