ABSTRACT
This work demonstrates and explains the effect of strontium modification on
machinability of aluminium-silicon eutectic (LM-6) type alloy. This alloy is known to have
many favourable features including great weight to strength ratio, high corrosion
resistance and excellent castability. However, LM-6 alloy has poor machinability, which
reduces its applications range. In this study, various samples of LM-6 alloy were cast
using sand and metallic chill mould with and without strontium addition. Machining on
each cast product, was carried out using recommended cutting parameters for Al-Si
alloys. Strontium modified samples have recorded a reduction in average flank wear, an
increase in shear plane angles and a reduction in chip thickness. The main reason for
this improvement is the refining effect of strontium, which reduces the size of the hard
silicon particles. As a result, their abrasive action on the tool face has reduced a lot.
Dramatic reductions in tool wear rate were also recorded only when the microstructures
were refined. On the other hand, when no refinement of microstructure occurs, tool
wear rate becomes high. The tool wear depends not only on the phases present in the
work material, but also on their sizes and distribution over the entire structure.