Measuring the fracture toughness of molybdenum-0.5 pct titanium-0.1 pct zirconium and oxide dispersion-strengthened molybdenum alloys using standard and subsized bend specimens

Abstract

Oxide dispersion-strengthened (ODS) and molybdenum-0.5 pct titanium-0.1 pct zirconium (TZM) molybdenum have excellent creep resistance and strength at high temperatures in inert atmospheres. Fracture toughness and tensile testing was performed at temperatures between − 150 °C and 450 °C to characterize 6.35-mm-thick plate material of ODS and TZM molybdenum. A transition from low fracture-toughness values (5.8 to 29.6 MPa√m) to values >30 MPa√m is observed for TZM molybdenum in the longitudinal orientation at 100 °C and in the transverse orientation at 150 °C. These results are consistent with data reported in literature for molybdenum. A transition to low fracture-toughness values ( −150 °C, while a transition to low fracture-toughness values (12.6 to 25.4 MPa√m) was observed for the transverse orientation at room temperature. The fine spacing of La-oxide precipitates which are present in ODS molybdenum results in a transition temperature that is significantly lower than any molybdenum alloy reported to date, with upper-bound fracture-toughness values that bound the literature data. A comparison of fracture-toughness values obtained using 1T, 0.5T, and 0.25T three-point bend specimens shows that a 0.5T bend specimen could be used as a subsized geometry.