Synthesis and Characterization of 17 Cr Ferritic ODS Steel Developed Through Vacuum Hot Pressing

Abstract

In the present investigation, on 17 Cr ferritic oxide dispersion strengthened (ODS) steel composition of (430L + 0.3Y2O3 + 0.5ZrO2 + 0.1Ti) wt% (alloy A) and (430L + 0.3Y2O3 + 0.5ZrO2 + 0.1Ti + 4Al) wt% (alloy B) were developed through mechanical alloying (MA) using VHP (vacuum hot pressing). The mechanically alloyed powders were taken at different milling time intervals for confirming the nanocrystalline size using X-Ray Diffraction (XRD). Finally, 20 h of milled powders were consolidated through vacuum hot pressing (VHP) at 1180 °C in the pressure levels of 60 MPa, and the cooling rate of 50°C/min. Throughout the experiments, the vacuum level was maintained by 10−3 Torr. Hot-pressed samples were subjected to densification studies; microstructural examination and hardness were analyzed in the current study. The nanocrystalline size of 3.6 nm (alloy A) and 6 nm (alloy B) were obtained at 20 h of milling time. The highest hot-pressed density of 7.60 g/cc (99% theoretical density) was acquired for aluminium-free ferritic ODS steel (alloy A) pressure at 60 MPa, whereas aluminium-contained alloy B lesser hot-pressed density of 7.34 g/cc was obtained. The microstructures of alloy A and alloy B containing ferrite along with complex oxides such as (Y–Zr–Ti–O) and (Y–Zr–Ti–Al–O), which is evident from TEM-EDS analysis. Alloy A has a higher hardness (870 VHN) due to the fine grains structure of material compared with alloy B (764 VHN).