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The alloy structural steel for gear shafts was treated by adopting a quenching and partitioning process, and effects of temperature and time of partitioning on the tensile properties, physical phase composition, microstructure and fracture morphology of structural steel were all explored. The results show that when the end temperature of fixed quenching and temperature of partitioning remain unchanged, extension of partitioning time can lead to gradual decrease in the tensile strength of the steel for gear shafts, and an increase followed by decrease in the fracture strain; with partitioning temperature at 225 ℃ and 275 ℃ respectively, the highest fracture strain is obtained at partitioning time of 120 s and 90 s, respectively; extension of partitioning time can lead to an increase followed by decrease in the strength-elongation product of the steel for gear shafts; the highest strength-elongation product can be obtained when the partitioning time is 90 s, and the strength-elongation product of the sample after quenching and partitioning treatment is obviously higher compared to the sample just treated by quenching. There is almost no residual austenite in the directly quenched sample, while the residual austenite in the sample by quenching and partitioning treatment is in a volume fraction of 3.0%-6.4%. It is found that at the same partitioning temperature, extension of partitioning time can result in martensitic tempering transformation, and carbide precipitation and growth in the steel for gear shafts.
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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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