Chepetsky Mechanical Plant JSC, Glazov, Russia:
D. A. Negodin, Chief Engineer of the Titanium Project, Non-Nuclear Business Development Group, e-mail: DmANegodin@Rosatom.ru
D. N. Kharkovskiy, Research Engineer
D. V. Dudikhin, Process Engineer

Hafnium possesses a unique complex of physical and chemical properties (high melting point, high corrosion resistance, enhanced structural behaviour not affecting the material ductility) that allow application of hafnium-based products in various industries. Hafnium is used mainly in nuclear power engineering, though it has also found application in production of heavy-duty batteries and permanent magnets, in release of mirror materials, integrated circuits and electronic devices. The only hafnium-producing enterprise in Russia is Chepetsky Mechanical Plant, SC (CMP, SC). By now, CMP, SC has mastered pilot scheme of production of metallic hafnium containing totally at least 99.8 wt % of zirconium and hafnium (Zr < 1 wt %), the ingots weighing up to 1 ton. The ingots are processed into the products for nuclear power engineering – flat stock and tubes. To expand the range of products, the efforts were made to master production of hafnium foil for radio engineering industry. The pilot batches of 0.10–0.30 mm thick foil were produced. The article provides comparative analysis of chemical composition of various hafnium grades and actual chemical composition of CMP, SC’s reported ingots. The foil manufacturing scheme with alternation of principal strain direction in cold rolling is described which ensures high uniformity of the material. Dependence of the hafnium foil’s mechanical properties on finish annealing modes is analyzed. It is shown that structural behaviour (tensile strength and yield strength) decreases, and ductility (percentage elongation) increases with increase of heat treatment temperature up to 950 ^oC. The results are provided of investigating the foil structural condition at various heat treatment modes. It is found that foil sheets’ microhardness decreases upon completion of heat treatment. Based on the study results, it is established that the hafnium foil production scheme developed by CMP, SC ensures isotropy of the properties.

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