Abstract: Some of cast slab of low carbon Si-Mn-B steel (% : 0. 16 ~ 0. 17C, 1. 10 ~ 1. 12Si, 1. 80 ~ 1. 85Mn, 0.001 0 ~ 0. 001 1 B) fractured in cross section after multiple conveying. The analysis on cast process, chemical coniposi- tion, structure and mechanical properties of slab showed that cast process for both fractured and un-fractured slab batch was same: for fractured slab, its S content was 0. 004% , P content was 0. 025% , middle crack rating 1. 5 and there was Irans- granular crack in structure ； for un-fractured slab, its S content was 0. 004% , P content was 0. 008% , middle crack rating 0 and the micro-crack wasn't observed in structure. The analysis results showed that higher P content in steel led to slab fracture, after multiple conveying.

Key words: Low Carbon Steel, Cast Slab, P Content, Middle Crack, Fracture

摘要： 低碳Si-Mn-B钢(%:0.16～0.17C、1.10～1.12Si、1.80～1.85Mn、0.0010～0.001 1 B)部分连铸板坯在多次搬运后发生横向断裂。对断裂与未断裂铸坯进行连铸工艺、铸坯成分、组织和力学性能的分析表明,二者连铸工艺相同,断裂板坯S含量为0.004%,P含量为0.025%,中间裂纹1.5级,组织中有穿晶裂纹,未断裂板坯S含量0.004%,P含量0.008%,中间裂纹0级,组织中未发现显微裂纹,说明板坯中P含量偏高导致板坯多次搬运后断裂。

关键词: 低碳钢, 连铸板坯, P含量, 中间裂纹, 断裂