Effect of Adding Machining Swarf of Brass Alloy on the Microstructure and Toughness of Gray Cast Iron

In this study, the effects of brass machining swarfs with different weight percentages on cast iron were investigated. The addition of 1 wt.% swarf contributed to the finer characteristics of the graphites categorized as types A and E while simultaneously increasing the quantity of pearlite grains present. When the amount of swarfs was increased to 3 and 5 wt.%, the graphite became finer due to rapid solidification, and a transitional interface of pearlite was also observed. The addition of 1 wt.% swarf to the cast iron led to an increase in hardness from 200 HB to 212 HB. However, as the swarf content increased, a reduction in hardness was observed, with the composites containing 3 wt.% and 5 wt.% swarf achieving hardness values of 197 HB and 185 HB, respectively. This phenomenon is linked to the presence of the softer brass phase in the composite structure. The microhardness of these swarfs was measured at approximately 99 Vickers, which was the minimum value. The soft phase of the swarf had a positive effect on increasing the impact energy due to ductile fracture, whereas the absence of the swarf led to brittle fracture in gray cast iron and the 1 wt.% composite. The impact energies of graycast iron and the 1 wt.%, 3 wt.% and 5 wt.% composites were measured to be 3, 4.2, 5.7, and 10.6 Joules, respectively.