Effect of Mechanical Alloying and Hot Consolidation Processes on the Microstructure and Mechanical Properties of ODS Steels

Microstructure of ODS steel significantly depends on its powder properties including the particle size, purity, and homogeneity after the MA process. The hot consolidation process is also very important to develop favorable microstructures. These fabrication processes should be carefully controlled to improve the mechanical property at high temperatures. In the present study, the effects of mechanical alloying conditions and hot consolidation process on the microstructure and mechanical properties of ODS ferritic steels are investigated. ODS ferritic steels were fabricated under various conditions to investigate the effects of mechanical alloying and hot consolidation process on the microstructures and mechanical properties. A slow milling speed made a heterogeneous grain distribution, and a long milling time resulted in high impurity inclusions in the microstructure. High HIP pressure was not sufficient to density the ODS ferritic steels. There were no significant effects of HIP temperature from 950 to 1150 .deg. C on the grain morphology and tensile strength. On the basis of these results, the fabrication process of 15Cr ODS steels could be optimized to have a favorable microstructure and tensile properties at high temperature