| 摘要 |
PURPOSE:To improve the corrosion resistance and mechanical characteristic of a Zr alloy pipe as a nuclear fuel cladding pipe by subjecting the Zr alloy pipe to a drawing stage until said pipe is reduced to the prescribed bore and wall thickness then heating quickly the pipe to a high temp. in an alpha region as a final heat treatment and cooling quickly the heated pipe immediately after holding for a short time. CONSTITUTION:A hollow billet consisting of a Zr alloy is hot-extruded and is then subjected to a drawing stage consisting of cold working, by which the billet is reduced to the finishing bore and wall thickness. The drawing stage is accomplished in combination with annealing at the intermediate and the final annealing is accomplished with 3-4 passes. The Zr alloy pipe subjected to the final annealing is quickly heated at the surface part up to 780-860 deg.C in the alpha region by, for example, high-frequency heating and after the pipe is held for several seconds, the pipe is quickly cooled so that the residual stress remains on the surface part. The nuclear fuel cladding pipe having excellent resistance to nodular corrosion, an excellent mechanical characteristic and less bending and twisting is thus obtd. |
