Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

The microstructure, composition and shape of precipitated piase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth (RE) amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0.2% in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10 -6-10 -5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0.10%-0.20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0.2% which leads to a largely improved high temperature mechanical property.