Microstructure and Mechanical Properties of Multi Pass Friction Stirred Processed Aluminium Silicon Carbide Metal Matrix

Abstract

Aluminium alloys of the 6000 series are known to have good formability, weldability, and high strength- to-weight ratio. The major alloying elements in the heat-treatable 6000 series are silicon and magnesium. Both elements are required for precipitation strengthening. Strengthening can be enhanced further by refining the grain size to a few micrometers and lower. This can be achieved by friction stir processing (FSP). An improvement in the mechanical properties was accomplished due to the micro structural modification of Aluminium alloy by multi pass friction stir processing (MP-FSP) which is a solid state micro structural modification technique using a frictional heat and stirring action. Samples with one through three passes with 100% overlap were created using friction stir processing (FSP) in order to locally modify the micro structural and mechanical properties of Aluminium Alloy. The micro structural properties in terms of particles distribution, and also the mechanical properties in terms of hardness and Surface Roughness of the processed zone were addressed with respect to the number of passes and traverse speeds.

In the present study, 2.5% (by weight) Sic  particles were incorporated by using Friction Stir Processing (FSP) into the 6351 Aluminium alloy to form particulate composite layered materials. Samples were subjected to constant rotational and traverse speeds of the FSP tool with and without Sic reinforcements. Samples were subjected to machining by Friction stir machining process on CNC machine with constant rotational and transverse speed by using HSS tools having 16mm and 18mm as diameter. Micro structural observations were carried out by employing optical microscopy of the modified surfaces. Mechanical properties were evaluated by Hardness test on vikers Hardness tester and Surface Roughness Values by Surface Roughness tester.