Effect of Grain Refinement on Corrosion Rate, Mechanical and Machining Behavior of Friction Stir Processed ZE41 Mg Alloy

Abstract

The aim of the present work is to modify the microstructure of ZE41 Mg alloy by friction stir processing (FSP) and to study the influence of microstructure on the corrosion, mechanical and machining behavior. Microstructural observations revealed the prevalence of grain refinement from ≈ 100 to 3.5 µm. The compound present at the grain boundary was observed to have decreased to a great extent after FSP suggesting the formation of supersaturated grains. Hardness measurements indicated increased hardness after FSP which was attributed to grain refinement effect. Tensile tests showed increased yield strength after FSP without altering the percentage of elongation which was due to the grain boundary strengthening. Corrosion performance of FSPed ZE41 was found to be similar compared with ZE41 due to the synergy of grain refinement, decreased amount of secondary phase and development of supersaturated grains. Grain size was observed as significant factor on machining characteristics as observed from improved machinability for FSPed ZE41 during drilling experiments. It was learnt from the current work that the grain-refined supersaturated ZE41 Mg alloy could be produced through FSP with better mechanical and machining behavior without deteriorating the corrosion performance. © 2018, The Indian Institute of Metals - IIM.