The low-alloy mild steel is characterized by its fine-grained microstructure and high ductility. Developed to avoid thermomechanical treatment compared to conventionally produced mild steels, the material has a high elongation capacity in the as-built state with yield strengths >360 MPa, which makes the steel a special choice on the AM metal powder market. In contrast to conventional fine-grained steels, the volume restrictions caused by the carbon content are strategically reduced, which opens up additional application possibilities. Related materials of m4p Fe-545 are S355 and 1.0545.