This forging ring includes forgings such as the central ring, fan ring, small seal ring, and water tank compression ring of the power station turbine generator, but is not suitable for non-magnetic ring forgings.
Manufacturing process:
1 Smelting
1.1. The steel used for forgings should be smelted in an alkaline electric furnace. With the consent of the purchaser, other smelting methods such as electro-slag remelting (ESR) may also be used.
1.2. For forgings of grade 4 or above and grade 3 forgings with a wall thickness of over 63.5mm, the molten steel used should be vacuum-treated or refined by other methods to remove harmful gases, especially hydrogen.
2 Forging
2.1. Each steel ingot should have enough cutting allowance to ensure forging quality.
2.2. Forgings should be formed on forging presses, forging hammers, or rolling mills with sufficient capacity to ensure full forging of the entire cross-section of the metal and to ensure that each section has sufficient forging ratio.
3 Heat treatment
3.1. After forging is completed, the forgings should be immediately subjected to preheating treatment, which can be annealing or normalizing.
3.2. The performance heat treatment is quenching and tempering (16Mn can use normalizing and tempering). The final tempering temperature of the forgings should not be lower than 560℃.
4 Chemical composition
4.1. Chemical composition analysis should be performed on each batch of molten steel, and the analysis results should comply with relevant standards.
4.2. Finished product chemical composition analysis should be performed on each forging, and the analysis results should comply with relevant standards. 4.3. When vacuum decarburizing, the silicon content should not exceed 0.10%. 4.4. For grade 3 ring forgings with a wall thickness of over 63.5mm, materials with a nickel content greater than 0.85% should be selected.
5 Mechanical properties
5.1. The tangential mechanical properties of the forgings should comply with relevant standards.
6 Non-destructive testing
6.1. The forgings should not have cracks, scars, folds, shrinkage holes, or other impermissible defects.
6.2. After precision machining, all surfaces should undergo magnetic particle inspection. The length of the magnetic stripe should not exceed 2mm.
6.3. After performance heat treatment, the forgings should undergo ultrasonic testing. The initial sensitivity equivalent diameter should be φ2 mm, and the single defect should not exceed the equivalent diameter φ4mm. For single defects between equivalent diameters of φ2mm~¢4mm, there should be no more than seven defects, but the distance between any two adjacent defects should be greater than five times the larger defect diameter, and the attenuation value caused by defects should not be greater than 6 dB. Defects that exceed the above standards should be reported to the customer, and both parties should consult on handling.
Post time: Nov-09-2023
