连铸坯中心偏析对LX72A钢帘线合股断丝的影响

Effect of Central Segregation of Casting Billet on Breakage of Steel LX72A Tire Cord in Stranding Process

70 t BOF-LF-Φ380 mm CC-开坯成150 mm×150 mm方坯-CR和200 t BOF-LF-200 mm×200mm CC-CR两种工艺路线所生产的Φ5.5 mm盘条经拉拔成Φ0.22 mm钢帘线合股过程的断丝率为Φ380mm圆铸坯工艺-2.86次/t,200 mm×200 mm方坯工艺-<1次/t。检验结果表明,圆坯工艺生产的盘条严重的中心偏析是大量断丝的主要因素,150mm×150 mm轧坯的宏观碳偏析高达1.11。采用断面尺寸200 mm×200 mm以上的方坯连铸工艺流程,中间包钢水过热度15～25℃,拉速恒定,采用结晶器和末端电磁搅拌,可有效地减轻中心偏析。

The breakage ratio in stranding process of Ф0. 22 mm steel tire cord cold-drawn from 05.5 mm coil produced both process flow sheet of 70 t BOF-LF-qb380 mm bloom CC-breakdown 150 mm × 150 mm billet-CR and 200 t BOF- LF-200 mm × 200 mm bloom CC-CR process is qb380 mm round bloom process-2. 86 times/t and 200 mm × 200 mm bloom process-less than 1 time/t. Examination results show that the main factor for massive cord breakage is distinct central segregation of coil produced by round bloom, and the macro carbon segregation of 150 mm × 150 mm rolled billet is up to 1.11. Using bloom casting flow sheet with cross section size more than 200 mm × 200 mm, control over heating degree of liquid in tundish 15 -25 ℃, constant casting speed and using mold and end electromagnetic stirring are available to decrease the central segregation.