Refer to the commonly used materials for heavy gear processing in China, consult the steel brand manual, and compare the material composition and mechanical properties of 18Cr2Ni4WA, a typical heavy gear processing material, with that of 3310 Chemical in the United States. The comparison results are shown in Table 1.
| Brand | C | Si | Mn | Mo | W | Cr | Ni | δb/ MPa | δ5/% | ψ/% | Impact energy/J |
| 3310 | 0.08-0.13 | 0.2-0.35 | 0.45-0.8 | — | — | 1.5-1.75 | 3.25-3.75 | 1160 | 10 | 43 | 63 |
| 18Cr2Ni4WA | 0.14-0.18 | 0.17-0.37 | 0.30-0.60 | — | 0.8-1.0 | 1.35-1.5 | 4.0-4.3 | 1175 | 10 | 45 | 78 |
The impact energy of domestic 18Cr2Ni4WA is better than 3310, and relevant tests and researches on heat treatment have been carried out. The content of residual austenite, carbide martensite and ferrite has been metallographically analyzed, and the surface hardness and core hardness have been tested, which meet the requirements of heavy gears. Finally, 18Cr2Ni4WA is selected as the raw material of domestic heavy gear for rocker arm transmission.
| Brand | C | Si | Mn | P | S | Cr | Ni | W | Cu |
| 18Cr2Ni4WA | 0.14-0.18 | 0.17-0.37 | 0.3-0.6 | ≤0.02 | ≤0.02 | 1.35-1.50 | 4.0-4.3 | 0.8-1.0 | ≤0.025 |
The raw materials of each batch of heavy gears shall be tested and inspected for grain size, end hardenability, non-metallic inclusions, mechanical properties, etc. in strict accordance with the internal inspection items and requirements of steel, as well as relevant national and international standards. The relevant quality standards are: the size of hot rolled round steel and its allowable deviation shall comply with the provisions of Group 2 of GB/T 702, both ends shall be cut flat, the cylindricity error shall not be greater than 75% of the nominal diameter tolerance, and the bending degree shall be ≤ 4 mm/m, Total bending ≤ 0.4% of steel length; The allowable deviation of main chemical components of raw materials and finished products shall comply with EN10084 standard; The chemical composition (smelting analysis) shall comply with the provisions in Table 2.