Method for forging and pressing semi-coupler with large section and high height-diameter ratio by using 31.5 MN of oil press

Abstract

The invention relates to a method for forging and pressing a semi-coupler with a large section and a high height-diameter ratio by using a 31.5 MN of oil press. A forging process route comprises the following steps of: upsetting; drawing; locally upsetting and forming by using a drain cap which is 1640 mm in outside diameter phi, 1100 mm in inside diameter phi and 310 mm in thickness; and thermally treating after forging: after forging a forged piece and air-cooling the forged piece till the surface temperature is 350+/-10 DEG C, putting the forged piece in a thermal treatment furnace, controlling the temperature of the treatment furnace at 450-500 DEG C, after keeping the temperature for 3 h, cooling to 280+/-20 DEG C with the furnace and keeping the temperature for 6 h, carrying out first super-cooling treatment, then raising the temperature to 650+/-10 DEG C and keeping the temperature for 6 h, then raising the temperature again to 890+/-10 DEG C, keeping the temperature and carrying out austenitizing treatment, lifting off a trolley, air-cooling through a fan, carrying out normalization treatment, air-cooling the forged piece till the surface temperature is 350+/-10 DEG C and putting the forged piece in the furnace, cooling the furnace to 260+/-20 DEG C and keeping the temperature for 7 h, carrying out second super-cooling treatment, raising the temperature to 650+/-10 DEGC and keeping the temperature for 40 h, tempering, carrying out diffusion hydrogen and white point resistant treatment, cooling the forged piece with the furnace till the temperature is less than or equal to 250 DEG C, and taking out the forged piece from the furnace. The method disclosed by the invention is simple in process, fewer in heating frequency and lower in energy consumption. The quality of the forged piece can be obviously ensured.

Description

technical field [0001] The invention relates to a forging method of a semi-coupling forging. It belongs to the technical field of metal forging. Background technique [0002] 1. Product technical requirements [0003] 1. 8 half couplings, the material is 34CrNi3Mo, see forging specifications figure 1 . Ultrasonic flaw detection according to JB / T7026-93 standard. [0004] 2. The maximum cross-section of this semi-coupling reaches Φ1505mm, and the height reaches 1050mm. There is neither a through hole nor a blind hole in the center, and it is a solid iron lump. When using small and medium-sized presses for forging, no matter whether it is produced by upsetting or elongated forging, since the energy of the press is quickly absorbed by the deformation of the surface metal, it is difficult to transfer the energy to the central part of the forging, and it is difficult to press the central part. Reality. If the central deformation is not sufficient, it is easy to form cast st...

AI Technical Summary

Problems solved by technology

When using small and medium-sized presses for forging, no matter whether it is produced by upsetting or elongated forging, since the energy of the press is quickly absorbed by the deformation of the surface metal, it is difficult to transfer the energy to the central part of the forging, and it is difficult to press the central part. Reality

If the central deformation is not sufficient, it is easy to form cast structures such as dendrites, and non-metallic inclusions and alloying elements are easy to precipitate along the grain boundaries of dendrites, which makes the plasticity of grain boundaries worse. When local upsetting rolling is adopted, it is easy to produce layered tear defect

34CrNi3Mo is a martensitic steel with strong white spot sensitivity. Under the combined action of stress and hydrogen ions in the metal, it is easy to produce dense ultrasonic flaw detection defects such as white spots and hydrogen embrittlement cracks, making production difficult.

[0005] The forging equipment is a 31.5MN hydraulic press. Due to the limitation of the forging capacity of the equipment, the shaft forgings with a cross-section exceeding φ1200mm and the disc-shaped forgings with a diameter exceeding φ1300 and a height-to-diameter ratio exceeding 0.6 are produced by conventional forging, and the pass rate of ultrasonic flaw detection is low. This has always been a difficult technical problem in forging production

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