METHOD OF MANUFACTURING HIGH PRECISION TUBING FROM HAFNIUM Russian patent published in 2019 - IPC C22F1/18 B21B3/00 B21J5/00 G21C3/07 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to production of pipes, tube half-finished products from metal hafnium with content of base metal not less than 98.8 wt%, used as structural material for active zones of nuclear reactors, in chemical and oil and gas industry. Method of making tubular articles from hafnium involves hot forging of ingot with intermediate heating, hot extrusion, multi-stage cold rolling with intermediate and finishing thermal treatment. Performing multi-junction hot forging of ingot at temperature interval 850÷1,100 °C at heating temperature 1,060÷1,100 °C with specified degree of deformation at each transition 20÷50 % and total degree of deformation of not less than 80 %. Hot extrusion of tube workpieces is performed in one stage with regulated drawing coefficient 5÷10. Mechanical processing of hot-blown pipe billets is performed with output of transverse difference to value of not more than 5 %. Multistage cold rolling is performed with deformation degree of 15÷45 % at each stage and total degree of deformation of not less than 80 %, before and after each heat treatment operation chemical etching is carried out.

EFFECT: high-accuracy hafnium tube articles are obtained while providing high yield.

7 cl, 1 tbl