Body sampling is required for vermicular graphite cast iron cylinder block. The sampling location and standard requirements are shown in Figure 1 and Table 1.
Through testing, the mechanical properties and metallographic structure of the compacted graphite cast iron cylinder block, each number represents a sample of the body, and the typical metallographic photos of the cylinder body are shown in Figure 2.
| Number | Position | Tensile strength/MPa | Hardness/HBW | Creeping rate/% |
| G | Thickened part of cylinder head bolt | 420~480 | 220~250 | ≥80 |
| Y | Oil pan flange | 420~480 | 230~260 | ≥80 |
| Z | Thickening part of main bearing cap bolt | 420~480 | 220~250 | ≥80 |
The mechanical properties and metallographic structure of the body sampling position meet the technical requirements. When the vermicularization rate is low, the strength is slightly higher, and when the vermicularization rate is high, the strength is slightly lower. The number of graphite spheres has a certain impact on the strength of vermicular graphite cast iron. Due to the difference of wall thickness at different positions of the cylinder block, the creep rate at each position is different. The wall thickness of the thickened part of the cylinder head bolt and the thickened part of the main bearing cap bolt is more than 30 mm, the creep rate is relatively high, and the wall thickness of the flange is less than 20 mm, the creep rate is relatively low.
