The phase transition temperature and static CCT curve at critical point of 800 MPa grade steel for hydropower project with low susceptivity to weld cracking are determined with phase change instrument Formast-F and the dilatation method combing with metallographic method as well as the effects of cooling rate on microstructure are studied. The results showed that the phase transition temperatures of test steel, Ac1 was 675 ℃, Ac3 was 875 ℃, Ar1 was 615 ℃ and Ar3 was 739 ℃; when the cooling rate was less than 0.25 ℃/s, the transformation products were ferrite (F) + pearlite (P) + a small amount of bainite (B); when the cooling rate was 0.25~1 ℃/s, the transformation products were ferrite (F)+ bainite (B); when the cooling rate was 1~5 ℃/s, the transformation product was bainite (B); when the cooling rate was 5~20 ℃/s, the transformation products were bainite (B)+ martensite (M); when the cooling rate was greater than 20 ℃/s, the transformation product was martensite (M).
| 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 |