PRODUCTION OF SEAMLESS HOT-WORKED MACHINED 610×36,53 mm FROM 15X5"M"-GRADE STEEL FOR REFINERY COMMUNICATIONS WITH STRINGENT REQUIREMENTS TO GEOMETRICAL SIZES Russian patent published in 2014 - IPC B21B19/04 

FIELD: metallurgy.

SUBSTANCE: production consists in smelting of ingots and forging to forged pieces. Said forged ingots are turned and bored to blanks, placed in continuous furnace in two rows and heated to ductility temperature under specified conditions. Then, they are discharged from the furnace and pierced at screw rolling mill at mandrel to sleeves-blanks. The latter are cooled at storage of blanks to ambient temperature and repaired is required. They are laid in one row and heated in continuous furnaces to ductility temperature under conditions whereat they are fitted on grate-bars of III-zone at 1000-1050°C. Then, they are held at grate-bars for 0.45-1.0 hours and turned along the furnace to 7^th opening at interval of 20-25 minutes through angle of 215-225°. Sleeves-blanks are heated to 1270-1280°C for 7.0-8.5 hours, held at 1270-1280°C for 0.45-1.25 hours with tilting along the furnace in 15-20 minutes from 7^th to 4^th opening. Then, they are tilted at pit and discharged from the furnace. Then, they are pierced-rolled at screw rolling mill at 485 mm diameter mandrel to rerolled sleeves-blanks sized to 650×500ID×3340-3540 mm and heat-treated. Then, they are bored and turned to finished-sizes pipes with surface smoothness Rz not over 40 mcm. Rings are cut off for mechanical tests, ends are trimmed, two-sized chamfering is performed, ultrasound control and inspection are carried out.

EFFECT: commercial pipes with stringent requirements to geometrical sizes and metal consumption index reduced to 2,250-2,280.

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