Stress rupture tests are conducted on DD10 alloy specimens with two distinct wall thicknesses at conditions of 1000 ℃/200 MPa and 1100 ℃/100 MPa. The stress damage characteristics of these specimens and the reasons for the thin-wall effect are analysisd. The findings reveal that, under both test conditions, the stress rupture life of thinner specimens is markedly shorter compared to thicker ones, indicating a pronounced thin-wall effect in DD10 alloy. Although the reduction in effective bearing area due to oxidation does expedite the creep process to some extent, the variation in effective stress increase across different wall thicknesses is minimal, within a range of just 6%. This suggests that the augmentation in effective stress stemming from oxidation is not the primary catalyst behind the thin-wall effect. Microstructural observations of the surface and longitudinal sections of the fracture reveal that, under both test conditions, the cavities and cracks in thinner specimens are smaller in size than those in thicker specimens. Furthermore, the relationship between the stress intensity factor(K) and crack length(l) indicates that, for cracks of equivalent size in specimens with varying wall thicknesses, thinner specimens exhibit a higher stress intensity factor at the crack tip, rendering the crack more prone to propagation. Consequently, thinner specimens have a shorter critical size for crack instability expansion. The disparity in this critical size among specimens with different wall thicknesses is pinpointed as a crucial factor contributing to the thin-wall effect.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |