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The rail head of 43 kg/m rail with material of U71Mn after induction hardening by user is cracked during straightening process. The rail is inspected with such methods as the chemical analysis, fractography, metallography detection and scanning electron microscope analysis. The results showed that the chemical composition could meet standard requirements, fracture morphology of fracture origin and microstructure were abnormal, melting holes and oxidation characteristics at grain boundary could be seen locally. The offline quenching induction heating process is judged to be abnormal. Different degrees of overburning and overheating are formed in near surface area at round corner on one side of rail, i.e. oxidation and melting at grain boundary. The abnormal microstructure of coarse cementite+ledeburite is formed after quenching so that the rail is cracked in subsequent straightening process.
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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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