Abstract
In the previous paper regarding the drilling machinability of Al-Si alloys, it was indicated that ununiformly dispersed silicon particles behaved as chip breakers, which played a significant role in chip treatment in drilling.
From this point of view, the probability of failure of silicon particles by tension or rolling are examined in this paper.
Various Al-Si alloys of different silicon contents were annealed at 520°C for 20 hrs. to spheroidize the particles, and then, were deformed to their corresponding degrees of strain. The longitudinal section in the direction of deformation of each specimen was polished and observed by optical microscopy.
As the results of this metallographic examination, the probability of failure was obtained with respect to various strains and particle diameters. The following equation was empirically deduced for tensioned specimens. PT=Cεnd where PT: the probability of failure of silicon particles by tension, C and n: constants, d: the particle diameter n is about 0.6 for eutectic silicon particles and 1.0 for pro-eutectic ones.
It was found that the probability of failur in a rolled specimen was higher than that in a tensioned specimen.
