Parts built in EOS MaragingSteel MS1 have a chemical composition corresponding to US classification 18Ni300. This kind of steel is characterized by having very good mechanical properties, and being easily heat treatable to obtain ultra high hardness and strength.
Parts built from EOS MaragingSteel MS1 are easily machinable after the building process and can be heat treated to 54 HRC by solution anneal and age-hardening at 490 °C (914 °F) for 6 hours. In both as-built and heat treated states the parts can be machined, spark-eroded, welded, shot-peened, polished and coated if required.