In this paper, Thermo-Calc software was used for composition design, and the temperature control rolling control cooling process was formulated in combination with the Continuous Cooling Transformation (CCT) curve measured by thermal simulation. By reducing the oxygen content of electric furnace tapping, optimizing the soft blowing process of external refining and adopting protective casting measures, type A inclusion level of hot rolled wire rod ≤1.0, type B inclusion level≤0.5, type C inclusion level=0, and type D inclusion level≤1.0, type Ds inclusion level=0. Ferrite-pearlite microstructure can be obtained by controlled rolling, temperature and cooling process, with tensile strength ≥ 740 MPa, elongation ≥ 22%, surface shrinkage ≥52%, total decarburization depth≤0.10 mm, grain size level ≥ 9 and cold forging meeting 1/3 of the requirements without cracking. The results indicate that the non-quenched and tempered cold heading steel developed in this research can be simultaneously used to make automotive chassis components such as steering ball pins, Grade 10.9 bolts, and brake system guide rods.
| 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 |