METHOD FOR PRODUCING HOT ROLLED COMMERCIAL AND CONVERSION TUBES WITH LARGE AND MEAN DIAMETERS FROM HARD-TO-FORM STEELS AND ALLOYS IN TUBE ROLLING PLANTS WITH PILGER MILLS

摘要

FIELD: rolled tube production, possibly in tube rolling plants with pilger mills.;SUBSTANCE: method comprises steps of casting hollow ingots with height 2000 - 3200 mm in electroslag refining plants; turning and boring ingots for removing scale and micro-crackings till diameter 400 -620 mm at relation of diameter to wall thickness D/S = 4.5 - 7.0 whose larger values correspond to ingot-sleeves of less diameters; rolling hollow ingot-sleeves heated till yielding temperature with relation D/S = 5.0 -7.0 and height 2000-2750 mm in pilger mill to commercial and conversion tubes with wall thickness up to 30 mm; rolling ingot-sleeves with relation D/S = 4.5 - 5.5 and height 2750 - 3200 mm in pilger mill to conversion tubes with wall thickness more than 30 mm.;EFFECT: lowered metal consumption, elimination from manufacturing process one operation of heating and piercing drilled ingots to sleeve, enhanced efficiency, increased length of conversion and commercial tubes with larger thickness of walls.;2 cl, 1 tbl