Full
Outline
Based on low carbon and Nb-Ti complex designing to trial-produce the two degrees ultra high strength automobile beam steels of 600 MPa grade (600L) and 700 MPa grade (700L), the produce processes and parameters of ultra high strength beam steels of 600 MPa grade and 700 MPa grade were also mentioned. Fatigue tests were performed on the steel sheets of both grades, along with bench fatigue tests on fabricated beam parts. The results showed that the fatigue limit of 700 L beam steel sheet was slightly higher than that of 600L beam steel sheet, while the fatigue ratio of 600L beam steel sheet was higher than that of 700L beam steel sheet. However, the bench fatigue life of the beam parts made from 600L beam steel sheet was much longer than that of 700L beam steel sheet. This indicated that the fatigue resistance of materials with different strength grades couldn’t be simply compared by fatigue limit alone. Instead, the fatigue ratio, by correlating the fatigue limit and static strength of materials, indirectly reflected the key characteristics of materials under cyclic loading, providing a more scientific and comprehensive characterization of the fatigue performance. The Cr+N micro-alloyed design in 600L beam steel sheet enhanced its fatigue performance through a triple mechanism of solid solution strengthening, fine grain strengthening and resistance improvement, which enabled the 600L beam steel sheet to achieve a stepwise improvement in fatigue performance.
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| 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 |
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