首钢SWRH82B线材异常组织成因分析

 首钢第一线材厂在生产SWRH82B线材过程中，盘条检测芯部出现异常组织现象：珠光体与残余奥氏体共存、索氏体与网状铁素体共存、索氏体与马氏体共存。通过对生产数据跟踪和扫描电镜观测发现，在冶炼、连铸过程中不稳定操作，铸坯中溶质元素碳、锰和铬元素偏析，钢液铬合金元素熔解不均匀，碳、锰和铬综合作用明显提高奥氏体的稳定性，大大推迟了奥氏体向珠光体的转变时间，在A1～Acm温度之间时间相对较长，形成残余奥氏体组织和珠光体、索氏体共存的局面；钢中溶质元素富集造成吐丝温度与相变之前冷速过快，形成片层间距不同的屈氏体和马氏体快冷低温组织。

Genetic Analysis for Abnormal Micro-Structure of Shougang SWRH82B Wire Rod

The abnormal microstructures of SWRH82B wire rod, such as pearlite and residual austenite concurrent, sorbite and net ferrite concurrent and sorbite and martensite concurrent, were detected by metallographic examination during production process of No.1 Wire Rod rolling mill of ShouGang. During steelmaking, segregation distribution of such solvent elements as carbon, manganese and chromium, and their combined action can noticeably increase austenite stability, and largely postpone the time of phase transformation from austenite to pearlite. The relative long time between A1 temperature and Acm temperature will lead coexistence phenomenon among residual austenite, pearlite and sorbite. During continuous casting process, constituent segregation will make cooling velocity too rapid and become microstructure of troostitic and martensitic with different lamina separations.