Machinability of 380 Alloy - Minor Impurity Constituent Effects

A small addition of magnesium (0.3%) to prime 380 die casting alloy (SAE 308) was found to improve the alloy's machinability. Magnesium hardens the matrix and by doing so

• reduces the tendency to build up on a tool edge,
• results in shorter and tighter chips,
• provides a better workpiece surface finish,

giving prime 380 desirable machining characteristics similar to those of secondary alloy. However, tool wear rates for the magnesium-modified prime alloy were significantly lower than those for secondary alloy.

Other minor/impurity element alloy variations also affected machining characteristics but less dramatically than the magnesium. Some elements traditionally credited with improving machinability were found in this study to be of little benefit.