FAILURE INITIATION POINT CONTROL IN BLOWN POWDER DIRECTED ENERGY DEPOSITION

Additive manufacturing defects are often cited as being detrimental to the final product and significant effort has been expended to mitigate said defects. However, in applications where failure of the component is a necessity to prevent undo wear and tear, these defects may be leveraged as a mechanism to control part failure location. This work explored the use of varying deposition parameters to induce failure of a component at a specified location. A blown powder directed energy deposition system coupled with a five-axis machine tool was utilized for the manufacture of test specimens. A thin section of a part was intentionally deposited with parameters, namely laser power, outside those known to produce dense components in an attempt to introduce lack of fusion porosity. Porosity within the band was shown to vary with changing laser power. Hardness testing of the components showed a vertical gradient along the build direction. A slight increase in hardness of 25 HV is noted at 2 mm above the intended failure region. Micrographs of the failure region revealed a distinct boundary between the failure region and the nominally correct regions. This work has shown that porosity location can be controlled in a directed energy deposition process.