Effect of the Strain Rate on the Mechanical Properties of Metalloceramic Molybdenumin the Ductile-Brittle Transition Temperature Range

摘要

Metalloceramic molybdenum is tested in the temperature range from -100 to +350°C and the strain rate range from 3.4 x 10~(-3) to 4 x 10~3 s~(-1). This wide strain rate range, which was used for the first time to study molyb-denum, makes it possible to find the laws of changes in its strength and deformation characteristics. It is found that the ductile-brittle transition temperature increases from -90 to +250°C in this strain rate range, the dependences of the lower and upper transition temperatures on the strain rate intersect at10~5.7 s~(-1), and the effect of the test temperature on the yield strength weakens with increasing strain rate and disappears at 10~5.9 s~(-1). The closeness of these two strain rates calculated using two different approximations suggests the presence of a certain limiting critical strain rate beginning from which molybdenum is in a brittle state.