The solubility of nitrogen is high in stainless austenite of steels with 18 mass% of Cr and Mn each, but low in the melt. Carbon reveals the opposite behaviour. Instead of producing high nitrogen steels by pressure metallurgy (PHNS), about 1 mass% of C+N is dissolved in the melt at ambient pressure. The new cost-effective C+N steel reaches a yield strength of 600 MPa, a true fracture strength above 2500 MPa and an elongation above 70 %. Conduction electron spin resonance revealed a high concentration of free electrons. Thus, the ductile metallic character of the C+N steel is enhanced, explaining the high product of strength and toughness.