耐磨钢BTW1板坯表面开裂缺陷分析

Analysis of surface crack defect of wear-resistant steel BTW1 plate

针对耐磨钢BTW1在热轧过程中出现板坯表面开裂的问题,选取典型缺陷试样,采用金相、扫描电镜以及能谱等分析手段,对开裂缺陷进行解剖分析。结果表明,BTW1热轧板开裂产生的原因是由于冶炼过程中B含量过量,导致凝固中产生氮化硼等B(C、N)复合碳化物,在奥氏体晶界产生沉淀,引起了晶界脆化。同时,以氮化硼为形核质点,氮化硼晶界析出及树枝晶区的偏析会导致碳化物偏聚形成带状碳化物,导致坯料塑性下降,在轧制过程中产生开裂缺陷。

Based on optical microscope, scanning electron microscopy and energy spectrum analysis, the surface crack defects of wear-resistant steel BTW1 plate have been analyzed. The results showed that the main cause of crack was the excess of B content in the refining process, which resulted in precipitation of BN or B （ C, N） composite carbides at austenite grain boundaries during solidification, then embrittled the grain boundaries. Additionally, BN segregation of grain boundary and dendrite segregation that nucleated with BN particles can cause the formation of banded carbide in slab, then decrease the plasticity of the slab.