Friction stir processing of commercial AZ31.pdf

AS p r b m h m ? K 1 ( t w e c d d d h o t t s d m K ( 0 dJournal of Materials Processing Technology 191 (2007) 77–81 Friction stir processing of commercial AZ31 magnesium alloy B.M. Darras, M.K. Khraisheh ?, F.K. Abu-Farha, M.A. Omar Center for Manufacturing and Department of Mechanical Engineering, University of Kentucky, USA bstract Recently friction stir processing (FSP) has emerged as an effective tool for enhancing sheet metal properties through microstructure modification. ignificant grain refinement and homogenization can be achieved in a single FSP pass leading to improved formability, especially at elevated tem- eratures. FSP is a solid-state process where the material within the processed zone undergoes intense plastic deformation resulting in dynamically ecrystallized grain structure. Most of the research conducted on FSP focuses on aluminum alloys. Despite the potential weight reduction that can e achieved using magnesium alloys, very little is reported on FSP of magnesium alloys. In this work, we examine the possibility of using FSP to odify the microstructure and properties of commercial AZ31B-H24 magnesium alloy sheets. The effect of various process parameters on thermal istories, resulting microstructure and properties are investigated. Preliminary results are promising and it is shown that FSP leads to finer and ore homogenized grain structure. 2007 Elsevier B.V. All rights reserved. ation; f p t n o c 3 s s U a n o r ueywords: Friction stir processing; Magnesium alloys; Microstructure modific . Introduction Friction stir processing is based on the friction stir welding FSW) technique which was invented by The Welding Insti- ute (TWI) in 1991 [1]. On observing the advantages associated ith FSW, mainly grain refinement, the phenomenon has been xtended to processing of commercial alloys. Friction stir pro- essing (FSP) is a solid-state process in which a specially esigned rotating cylindrical tool, consisting of a pin and a shoul- er, is plunged in