Processing Method for Large Cr-Ni-Mo-V Steel Connecting Shaft Used in Nuclear Power Unit

Abstract

The present invention discloses a processing method for a large-sized Cr-Ni-Mo-V steel connecting shaft used in a nuclear power unit, which includes an ingot smelting process, a forging process, a post-forging heat treatment process, and a property heat treatment process. Among them: in the ingot smelting process, a Cr-Ni-Mo-V double-vacuum steel ingot is smelted by using the EBT+LF+VD+VC process; the forging process includes the first forging, the second forging, the third forging, and the fourth forging. In the first forging, the ingot is pressed at the handle, drawn out, and billets are formed. The bottom part is pressed at the tong handle separately. In the second forging, upsetting and WHF billet preparation are carried out. In the third forging, upsetting and stepped billet formation are carried out. In the fourth forging, combined die forming is carried out; in the post-forging heat treatment process, normalizing at high and low temperatures twice + hydrogen diffusion annealing is carried out; in the property heat treatment process, normalizing + quenching and tempering are used for property heat treatment. The processing method of the present invention can ensure the internal structure and mechanical properties of the forging, meet the flaw detection and composition requirements, and can also ensure high dimensional accuracy, improve processing efficiency, and reduce processing costs.

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