Development of mechanical performance of 12YWT steel nanocomposite by addition of zirconium and tantalum

The 12Cr-3W-0.4Ti-0.25Y2O3 (12YWT) Oxide dispersion strengthened ferritic steel shows a good strength up to 600 °C, while degrades considerably beyond that. In addition, this steel undergoes a week ductile to brittle transition temperature. Studies were made to improve of both strength and DBTT. Hence, the mechanically alloyed powders containing different contents of Zr (0.5-1.5%) and Ta (0.05-0.15) were extruded at 850 °C and mechanical properties of these steel nanocomposites were investigated. Mechanical analysis studies indicated that the addition of zirconium element can improve mechanical properties. For example, the presence of 1.5% zirconium in 12YWT resulted in an unprecedented value of 2100 MPa for tensile strength and improved ductile to brittle transition temperature of −27 °C. In contrast of zirconium, increase of tantalum did not change remarkably tensile strength of 12YWT. However, Charpy impact test results presented that tantalum have an important role in improved ductile to brittle transition temperature so that this parameter changed from 13 °C to −44 °C at presence of 0.15% Ta.