Effect of Friction Stir Processing at High Rotational Speed on Aging of a HPDC Mg9Al1Zn

Metals

Emanuela Cerri¹  Emanuele Ghio¹ 

[1] Department of Engineering and Architecture, University of Parma, 43124 Parma, Italy;

关键词: FSP;    HPDC AZ91;    post-process aging;    no solution treatment;   

DOI  :  10.3390/met10081014

来源: DOAJ

【 摘 要 】

Friction stir processing (FSP) has confirmed its valuable contribution to refining microstructures and the improvement of mechanical properties for Mg-Al alloys. Reference papers illustrate that post-processing aging treatments enhance hardness, but with the application of a solution heat treatment prior to FSP. In this work, aging was performed at two different temperatures (170 and 300 °C) directly on friction stir processed samples of AZ91 produced using high pressure die casting (HPDC). High rotational speeds of the tools (2500 and 3000 rpm) increases the heat input and the temperature of the plates during the process up to 270 °C. Vickers microhardness (HV) increased by 15–20% in the nugget, compared to the as FSPed condition; moreover, a greater homogeneity of hardness values was found at the higher aging temperature used. The β-Mg₁₇Al₁₂ precipitates are randomly distributed inside grains of the stirred area, while in the thermomechanical affected zone (TMAZ) they have grown in a network similar to the old eutectic. A preliminary investigation of FSPed samples deformed at 300 °C found that an equivalent hardness increase is achievable using hot deformation due to dynamic precipitation; to find local homogeneity in hardness, it is worth performing a final aging.

【 授权许可】

Unknown