Microstructure Evolution of Stainless Steel during Laser Metal Deposition Shaping

Laser Metal Deposition Shaping (LMDS) is a process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, 3-dimensional metal components. A variety of materials have been processed with LMDS, ranging from stainless steel to superalloy. To evaluate the processing parameters and resulting microstructures, solidification studies have been performed on defined alloy systems. For example, solidification cooling rates and growth velocities have been determined based upon secondary dendrite arm spacings formed during solidification in stainless steel. Corresponding to the great change of cooling rates, growth rates vary dramatically. As a result, process definition has been developed based upon the microstructure evolution during solidification.