2014 Volume 100 Issue 8 Pages 943-950
High strength Mn-Cr-N steels containing high nitrogen contents were manufactured using a lab-scale pressurized electro-slag remelting furnace to determine the deformability of the steels. Melting experiments were performed under a condition of 1.0 MPa pressure N2 gas to have various N contents. Gas porosity and severe macrosegregation were not observed in the remelted ingots. Microstructure observation revealed that nitrides and non-metallic inclusions were small enough without affecting the mechanical properties. After the ESR ingots were heat-treated and forged, mechanical properties of the steels at a room temperature were measured. The grain sizes were measured as the range from 50 to 300 μm. The results of 0.2% proof stress showed that the steel became stronger with increasing N content according to solid solution hardening mechanism. In addition, with various strain rates, tensile work hardening exponents were determined to be almost constant values between 0.20 and 0.25. These results suggest that the method of cold working for the 18Mn-18Cr-0.7N steel is applicable to the Mn-Cr-N steels containing nitrogen over 1.0 mass%.
