Within the field of Advanced High Strength Steels (AHSS), high-manganese Transformation- (TRIP) and Twinning-Induced Plasticity (TWIP) steels have gained strong commercial interest due to their outstanding mechanical properties. However, wide industrial application of these steels has been impeded so far due to their comparatively high alloying and processing costs. Production of high-manganese steels using Additive Manufacturing (AM) may be a promising alternative to overcome shortcomings related to conventional processing. Metal AM received enhanced scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts as well as reduced equipment costs. Amongst various AM methods, Selective Laser Melting (SLM) and Laser Metal Deposition (LMD) are now eligible techniques for production of fully dense bulk material with complex geometry.
In this presentation, the application of SLM and LMD for processing high-manganese TRIP and TWIP steels will be addressed. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using OM, SEM, EBSD, and EDX. The deformation behavior was studied using uniaxial tensile testing in addition to microstructure characterization. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM and LMD. Also, the very fast cooling promoted ε- and α’-martensite formation prior to deformation. The influence of the different production techniques on the microstructure and the related microstructure-property-relationships will be discussed.