Forged Material:
20MnNi and 20MnNi.
Mechanical Properties:
For a forging thickness (T) between 300mm < T ≤ 500mm, the material 20MnNi should have a yield strength ≥ 265MPa, tensile strength ≥ 515MPa, elongation after fracture ≥ 21%, reduction of area ≥ 35%, impact absorption energy (0℃) ≥ 30J, and no cracks during cold bending.
For a forging thickness (T) greater than 200mm, the material 25MnNi should have a yield strength ≥ 310MPa, tensile strength ≥ 565MPa, elongation after fracture ≥ 20%, reduction of area ≥ 35%, impact absorption energy (0℃) ≥ 30J, and no cracks during cold bending.
Non-Destructive Testing:
Different non-destructive testing methods such as ultrasonic testing (UT), magnetic particle testing (MT), liquid penetrant testing (PT), and visual inspection (VT) should be performed on various regions of the main shaft forging at different stages and conditions. The testing items and acceptance criteria should comply with relevant standards.
Defect Treatment:
Excessive defects can be removed by grinding within the machining allowance range. However, if the depth of defect removal exceeds 75% of the finishing allowance, welding repair should be carried out. Defect repair should be approved by the customer.
Shape, Dimension, and Surface Roughness:
The forging process should meet the dimensional and surface roughness requirements specified in the order drawing. The inner circle surface roughness (Ra value) of the forging shall be processed by the supplier to achieve 6.3um.
Melting: The steel ingots for forging should be produced through electric furnace melting and then refined outside the furnace before vacuum casting.
Forging: Adequate cutting allowances should be provided at the sprue and riser ends of the steel ingot. Forging should be performed on capable forging presses to ensure sufficient plastic deformation of the entire cross-section of the forging. It is recommended to have a forging ratio greater than 3.5. The forging should closely approach the final shape and dimensions, and the centerlines of the forging and steel ingot should align well.
Heat Treatment for Properties: After forging, the forging should undergo tempering or normalizing and tempering treatment to obtain uniform structure and properties. The minimum tempering temperature should not be lower than 600°C.
If you need more info about WELONG forgings for large gear and gear ring, kindly let us know.
Post time: Jan-08-2024
