PRODUCTION OF HEXAGONAL PIPE BILLETS FOR COMPACT STORAGE AND TRANSPORTATION OF USED NUCLEAR FUEL FROM LOW-DUCTILE STEEL WITH BORON CONTENT OF 1,3-3,5% Russian patent published in 2015 - IPC B21B21/00 

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Ingots-billets sized to 500±2×ID330±2×2750±50 mm are fitted on grate bars at continuous furnace centre at temperature in third zone of 800-850°C and held without turnover for 45-60 minutes and heated to 550-600°C. Ingots-billets are turned over by one opening in 20-22 minutes. Here, ingots-billets from 22^nd through 7^th openings are uniformly heated to 1080-1100°C at the rate of 1.3-1.5°C/min and held for 45-50 minutes at 1080-1100°C with uniform turnover from 7^th to 4^th opening in 15-17 minutes. From 4^th opening said ingots-billets are turned over to pit and discharged onto ingot truck at centre temperature of 1080-1100°C. They are blown with compressed air to feed the mix of table salt with graphene (50/50) in amount of 800-1000 g. Now, they are carried to Pilger mill inlet and rolled to 325×12×22400-23300 mm rerolled pipes. Pipe units are cut by hot cutting saws to 7450-7750 mm lengths, bored and turned to rerolled 321×8×7450-7750 mm lengths with surface smoothness R_z≤30 mcm. The latter are heated in inductor to 200-250°C and rolled at CPR 450 milled to rerolled 284.8×6×10500-11000 mm pipes. Ultrasound control is performed; ingots-billets are shaped to hexagonal pipe billets to be cut to 257+2/-3×6+2/-1×4300+80/-30 mm pipe billets to proceed with further jobs.

EFFECT: production of cold-rerolled pipes of precise sizes for shaping to hexagonal pipes, lower metal input.

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