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采用扫描电镜/能谱仪表征高强度结构钢中夹杂物的特征,考察了钛合金化及钙处理对钢中夹杂物组成的影响,探讨了氧化物对TiN析出行为及其对微观组织的影响。结果表明,钛合金化后钢中的夹杂物多为球形或多边形的Al-Ti-Mg-O系,钙处理能有效球化钢中的夹杂物和还原夹杂物中的TiOx,还原的Ti逐渐向夹杂物表层扩散积聚,促进了TiN在复合氧化物表面局部析出。钢中细小氧化物及氮化物的数量随Ti含量增加而增加,因此,钙处理较高Ti含量钢有助于促进细小的复合氧化物+TiN夹杂物的形成,并延迟凝固过程中TiN均质形核时间,细化TiN颗粒的尺寸。2~3μm的TiN不仅能诱导多边形铁素体析出,也能诱导针状铁素体析出。TiN及MnS在复合氧化物表面局部析出有助于互锁的针状铁素体诱导析出。
The characteristics of inclusions in high-strength structural steel were characterized by scanning electron microscopy and energy dispersive spectroscopy. The effects of titanium alloying and calcium treatment on the composition of inclusions in steel were investigated. The effects of oxides on TiN precipitation and its microstructure were discussed . The results show that the inclusions in the steel after titanium alloying are mostly spherical or polygonal Al-Ti-Mg-O system. Calcium treatment can effectively inclusify the inclusions in the steel and reduce the TiOx in the inclusions. The reduced Ti gradually Diffusion accumulation to the inclusions surface layer promotes the local precipitation of TiN on the surface of the composite oxide. The amount of fine oxides and nitrides in steel increased with the increase of Ti content. Therefore, the higher content of Ti in steel increased the formation of small composite oxides + TiN inclusions and delayed the homogenization of TiN during solidification Nucleation time, refine the size of TiN particles. TiN 2 ~ 3μm can not only induce polygonal ferrite precipitation, but also induce acicular ferrite precipitation. Local precipitation of TiN and MnS on the surface of the composite oxide facilitates the formation of interlocking acicular ferrite-induced precipitation.