The 590CL wheel steel is formed by spinning and stamping technologies to be made into automobile spoke. There is cracking in the process of stamping air hole. The cracking position is determined to be between the air hole on outer edge of spoke and shear end as well as fracture origin is at the air hole end of wheel steel, which is about the central part of plate thickness through macroscopic observation of cracked wheel steel as well as such comprehensive analysis as scanning electron microscope and metallographic examination; the zone of segregation in the core of wheel steel with inclusions those are mainly C and Nb in shape of dot string could all hinder normal deformation of ferrite in pre-forming process so that the fluidity of metal is inconsistent. As a result, the work hardening is generated and stress concentration in segregation in the core induces cracks, then stress is released through punching so that cracking is caused. It is suggested to adjust the composition to ensure appropriate proportions of niobium and carbon as well as optimize processes of steelmaking, continuous casting and rolling in the future production and processing processes.
| 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 |