The influence of pre heat treatment on gear heat treatment deformation, and the results are analyzed according to the scheme and implementation.
The test results of isothermal annealing hardness and normalizing hardness of 9t first speed gear blank are shown in Table 1;
| Pre heat treatment method | Hardness of gear blank (HB) | Sheet P + F level | Banded organization level |
| Isothermal annealing | 160-180 | 1 | 1 |
| Normalizing | 190-240 | 3 | 2 |
The microstructure of gear blank after isothermal annealing is shown in Figure 1;
See Table 2 for gear carburizing results;
| Name | Surface hardness | Core hardness | C | M | A’ | F | Hardened layer depth HV550 | Conclusion |
| One speed gear | HRC61 | HRC35 | 1 | 2 | 2 | 1 | 1.10mm | Qualified |
