The effect of stress concentration on the mechanical properties of molybdenum specimens with a protective coating in tests in an oxidizing atmosphere

Abstract

1. The short-term strength of smooth specimens at 800–1500 °C is lower than the strength of specimens with notches. 2. The values of the ultimate strength obtained in tests on all types of specimen in air are somewhat lower than the corresponding values obtained in vacuo. 3. The ductility of notched specimens in tests in an oxidizing atmosphere is two or three times lower than that of smooth specimens. 4. The nature of the ɛ-t relationship for smooth specimens in vacuo is similar to that in air. 5. The value of the plastic deformation at which cracks appear in the coating depends to a large extent on the rate of plastic deformation and the temperature. 6. The extent of plastic deformation in creep and long-term strength tests on smooth specimens in air is twice as low as in tests in vacuo, whereas for notched specimens they are practically the same. 7. The long-term strength of coated specimens in air is practically the same as that of the base in vacuo. 8. The long-term strength of smooth specimens tested in an oxidizing atmosphere is practically the same as that of notched specimens.