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The ultrasonic flaw detection of fixed flash welding joints for 60 kg/m-U75V rail is carried out in a welded rail base. It is found that there is excessive alarm of flaw detection at the rail bottom corner at welding line. The joints with defects are analyzed through metallographic observation, detections with scanning electron microscope and energy dispersive spectrometer (EDS). The results showed that the lack of fusion and hole defect were observed at weld bond at rail bottom of welded joint at the position marked by rail detecting as well as there were gray spots and abnormal bulk inclusions at fracture of bending. Analysis suggested that the main causes of flaw detection alarm were the lack of fusion and hole defects caused by formulating improper welding process parameters as well as excessive inclusions in base material. The defects could be reduced by optimizing welding process and improving metallurgical quality of base material.
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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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