Effect of powder characteristics on microstructure and properties of 30CrMnSiNi2A steels

The 30CrMnSiNi2A steel powders were prepared by water atomization (WA), gas atomization (GA), and plasma rotating electrode process (PREP) in this paper. The characteristics of the different atomized powders and the microstructure and properties of the sintered products were compared and analyzed. The results show that, the characteristics of the different atomized powders are different, such as morphology, particle size distribution, oxygen content, and fluidity. The hollow powders and satellite powders exist in the WA and GA powders. The PREP powders have no internal defects, showing the excellent fluidity and the lowest oxygen content. The microstructure of the sintered products using the three atomized powders is granular bainite, but the morphology of the prior particle boundary (PPB) is different. With the decrease of the powder oxygen content, the inclusion size at the PPBs decreases, and the composition changes from Al-rich oxide to Al-Si-rich oxide. Compared with WA and GA powders, the sintered product using PREP powders has the best tensile properties with the tensile strength and elongation of 1310 MPa and 11.5%, respectively, which benefit from the good powder quality and low oxygen content.