Mitigation of lack of fusion defects in powder bed fusion additive manufacturing

Components manufactured by additive manufacturing often exhibit improper fusion among layers and hatches. Currently, there is no practical way to select process parameters and alloy systems based on scientific principles to mitigate these defects. Here, we develop, test and demonstrate a methodology to predict and prevent these defects based on a numerical heat transfer and fluid flow model for the laser powder bed fusion (PBF) additive manufacturing (AM). These defects are avoidable by adjusting laser power, scanning speed, layer thickness and hatch spacing. An easy to use parameter is proposed for practical use in shop floors. Relative susceptibilities of three widely used AM alloys are demonstrated using this parameter.