CSP连轧过程中低碳钢的组织变化规律

STUDY ON MICROSTRUCTURE EVOLUTION OF LOW CARBON STEEL DURING CONTINUOUS ROLLING IN CSP

对珠钢CSP生产现场同一低碳钢轧件的铸坯及不同道次变形后室温组织的研究表明 :铸坯组织由细晶区 (急冷层 )和树枝晶区组成 ;随轧制道次增加 ,变形后轧件的室温组织细化 ,沿铁素体晶界分布的珠光体变得均匀、弥散 ;连轧前铸坯表面和心部的组织差异随着轧制道次增加逐渐减小。珠钢成品板组织细化的原因可以归结为大压下连轧工艺 ,钢中大量弥散析出的氧化物、硫化物和终轧后的层流冷却。

An investigation was carried out on the microstructure evolution of low carbon steel durng continuous rolling in CSP The specimen, cut from slab and strip after each pass, were examined metallographically The microstructure of slab consists of fine crystal zone(rapid cooling layer) and dentritic crystal zone It was revealed that the microstructure after (n+1)th pass is finer than after nth pass during continuous rolling The ferrite, distributed along the grain boundries of ferrite, becomes more uniform and dispersive gradually The difference in microstructure between surface and center of slab is gradually decreased during continuous rolling It can be concluded that recrystallization of austenite at high temperature and strain accumulation at lower temperature contribute to formation of finer microstructure The remarkable grain refinement can be caused by precipitation The controlled cooling after rolling is also beneficial to grain refinement