Method of manufacturing tubular products from a zirconium alloy

Abstract

The invention relates to manufacturing tubular products from a zirconium alloy, which can be used as cladding tubes in water-cooled nuclear reactors. Claimed is a method of manufacturing tubular products from a zirconium alloy containing 0.9-1.7 wt% niobium, 0.10-0.20 wt% iron, 0.10-0.20 wt% oxygen, less than 0.02 wt% silicon, less than 0.02 wt% carbon, and zirconium as the base of the alloy, which includes melting an ingot, mechanically treating the ingot, heating same, carrying out multi-stage hot forging, heat treating the forged workpiece, subsequently carrying out mechanical treatment and vacuum heat treatment, applying a protective coating to the tubular blanks produced, hot pressing, removing the protective coating, carrying out vacuum heat treatment, and carrying out multi-pass cold rolling with an overall reduction of 58-74% per pass and a tubular coefficient of Q=1.18-2.01, with vacuum heat treatment being carried out between passes. The final vacuum heat treatment is performed at the final size, followed by a finish machining operation. The technical result is an improvement in the processability of the material for manufacturing the pipe product in each stage of the hot and cold press treatment, and a high corrosion resistance of the pipe product with stable mechanical properties and resistance to shape changes.

Description

technical field [0001] The invention relates to the field of nuclear engineering, in particular to a method for manufacturing pipe products from zirconium alloys (used for water-cooled nuclear reactors, especially for shell tubes and channel tubes of VVER reactors). Background technique [0002] Zirconium alloys are used as materials for structural elements of power nuclear reactors due to their unique properties: small thermal neutron absorption cross section, corrosion resistance in high temperature water and water vapor, resistance to oxidation and hydrogenation, small radiation growth and other physical and mechanical performance. The performance of tube products depends on the chemical composition and each process operation, starting from ingot melting and ending with finishing. [0003] There is a known "Process (Variants) for the manufacture of tubular products from zirconium alloys" (RU 2123065S1 publ. March 12, 1997, CL C22R / 1 / 18), which consists in obtaining a sta...

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Problems solved by technology

[0008] The main disadvantage of this method is the small development of the cold-rolled material, with a total deformation of up to 60% per pass, which leads to an incomplete elimination of the uneven hot-rolled structure

In addition, the method has the disadvantage of using a steel sleeve containing carbon, which interacts with the zirconium alloy at hot rolling temperatures, possibly forming carbides

At the same time, the characteristic deterioration of the resistance to shape change is mainly due to the incompleteness of the recrystallization process

The technical solution does not provide for finishing operations, enabling the removal of residual technical contamination from the surface of the pipe product and the reduction of surface roughness, which reduces the corrosion resistance of the product

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