Development of Fe−12%Cr mechanical-alloyed nano-sized ODS heat-resistant ferritic alloys

Abstract

The development of mechanical alloying (MA)-oxide dispersion strengthened (ODS) heat-resistant ferritic alloys of Fe-12%Cr with W, Ti and Y203 additions were carried out. Fe-12%Cr alloys with 3%W, O,4%Ti and 0.25% Y 203 additions showed a much finer and more uniform dispersion of oxide particles among the alloy system studied. Nano-sized oxides dispersed in the alloys suppress the grain growth during annealing at a high temperature and resulted in the remarkable improvement of creep strength. The oxide phase was identified as a complex oxide type of Y-Ti-O.

Effect of Ti and W on the Mechanical Properties and Microstructure of 12% Cr Base Mechanical-alloyed Nano-sized ODS Ferritic Alloys

“…Figure 6 shows the creep rupture strength of the 12YWT alloy as Larson-Miller plot in simple creep testing comparing with other data. 4,14,[24][25][26][27] This result also shows the same Table 2. Dispersion parameters and void-hardening stress evaluated from transmission electron micrographs.…”

“…Hereafter, mass% is used in this study. The 12YW alloy is a version of modified 12Y1 alloy having a basic composition with 3 % W. The 12YWT alloy is another version of modified 12Y1 alloy with 3 % W and complex oxides of Y and Ti which have been developed recently [12][13][14] and was provided by Kobe Steel Ltd. in Japan. Y 2 O 3 serves as an accelerator, and the content of Y 2 O 3 was limited to about 0.25 % (powder diameter: about 20 nm) in order to improve recrystallization behavior.…”

“…Behavior Figure 8 14) shows the TEM photographs of the specimens air cooled after annealing at 1 323 K for 1 h. Figure 9 shows TEM photographs of the same specimens re-annealed at 1 523 K for 10 h and showing the observation of recrystallization behavior. The results showed that matrix microstructures of the 12Y1 and 12YW specimens were recrystallized, followed by grain growth, up to the average size of about 10-20 mm.…”

Unusual thermal stability of nano-structured ferritic alloys

“…Excellent mechanical properties are obtained, for example, by mechanical alloying of ferritic steel with only minor addition of Ti and Y 2 O 3 (≤0.5 wt.%) [1][2][3][4][5][6][7][8][9][10][11][12][13]. At temperatures between 650 and 900 • C, the creep rate of Fe-14Cr-3W + 0.25Y 2 O 3 + 0.4Ti (wt.%) (hereafter designated as 14YWT) ferritic alloy is six orders of magnitude lower as compared to the similar cast materials [5].…”