Nanosized precipitates in H13 tool steel low temperature plasma nitriding

► The effectiveness of plasma nitriding in low temperature (400 °C) is reported. ► HR-TEM analysis shows coherent chromium nitride nanosized precipitates. ► 9 hours nitriding process builds a ~ 43 μm case without large precipitates. ► Relative high nitrogen concentration (~ 12at%) is measured in the diffusion layer. ► The nitrided case hardness can reach up to 14.5 GPa for AISI H13 tool steel.