In-situ full-field mapping of melt flow dynamics in laser metal additive manufacturing

•Developed the full-field melt flow mapping approach to study melt flow dynamics under additive manufacturing conditions.•Revealed the location-specific flow patterns and quantified the speeds of various types of flow.•Reconstructed three-dimensional flow pattern under both conduction-mode melting and depression-mode melting.•Experimentally analyzed the prevailing physical processes at different locations in the melt pool.