METHOD FOR PRODUCING COVER HEXAHEDRAL TUBE-BLANKS OF LOW-DUCTILE BORON-CONTAINING STEEL FOR COMPACTED STORAGE OF WASTE NUCLEAR FUEL Russian patent published in 2008 - IPC B21B21/04 B21B23/00 B23P6/04 

FIELD: production of cover hexahedral tube-blanks of low-ductile boron steel for compacted storage of waste nuclear fuel, possibly manufacture of hexahedral tube-blanks of given size, restoration of rejected hexahedral blanks after boring, turning and repairing of their outer surfaces according to rolling-origin flaws.

SUBSTANCE: method comprises steps of rolling conversion tubes with size 290 x 12 x 2100-2200 mm; cutting tube lengths by means of hot cutting saw by tubes; marking out tubes for cutting by blanks; marking blanks; cutting tubes by blanks; measuring geometry parameters of blanks; straightening blanks with common curvature along length more than 3.0 mm; boring blanks for further quality control of their inner surface and inner diameter; marking blanks inside by means of paint; forming inner and outer chamfers; turning blanks in machine tools with servo system; technologically controlling wall thickness of blanks; inspecting and repairing defect zones of outer surface; measuring thickness of wall; repairing zones of outer surface having flaws and thickness of wall outside plus limit size; performing secondary turning if necessary; transferring number of blank by means of stamps onto outer surface of blanks; degreasing blanks; subjecting blanks to induction heat treatment, ultrasound flaw detection and to spectroscope control; drilling openings for drawing chain for profiling on marked ends of blanks; applying salt lubricant onto blanks; warm shaping of hexahedral blanks; controlling geometry sizes of hexahedral blanks; degreasing them; heat treating hexahedral blanks; controlling size 257 ± 2 x 6 + 1.75/-1.0 mm; correcting portions whose sizes are outside plus allowance field; controlling total curvature of faces along length of hexahedral blanks; marking out and cutting hexahedral blanks by measured length 4300+80/-20 mm; selecting templates in order to make samples for mechanical testing; transferring marking; removing fins, trimming and blowing through hexahedral blanks; straightening in press hexahedral blanks with curvature more than 3.0 mm along length of tube-blank; inspection after straightening curvature and controlling size; controlling hexahedral blanks for passing templates through them; straightening if necessary; controlling geometry size of hexahedral blanks; trimming portions of hexahedral blanks whose sizes are outside plus limit values along wall thickness and finish sizes; reception; brightening; testing metal templates of hexahedral blanks by mechanical properties; final reception; marking and packaging hexahedral tube-blanks. Blanks after boring, turning and repairing flaws of outer surface with wall thickness in repairing places less than 5.0 mm are fed for further operations of manufacturing process including degreasing of blanks and then flaw zones are repaired by electric arc surfacing under flux layer or in argon shield atmosphere by means of electrode of boron steel. Repaired zones are subjected to grinding till predetermined wall thickness and smooth joining with planes of hexahedron and then they are subjected to heat treatment at performing all next technological operations according to manufacturing process.

EFFECT: lowered metal consumption, reduced cost of commercial hexahedral tube-blanks.

3 cl, 1 tbl