镁处理对45钢中夹杂物的改质效果

采用光学显微镜、扫描电子显微镜、非水溶液原位电解方法对比分析了镁处理(0.0006%Mg)和钙处理(0.0010%Ca) 45钢中夹杂物类型、尺寸、分布及形态变化。研究表明,相对于传统的钙处理工艺,45钢中加入一定量的镁后,钢中的Al₂O₃转变为细小弥散的MgO·Al₂O₃,MnS在凝固末期以MgO·Al₂O₃为形核质点,形成外软内硬的MnS-MgO·Al₂O₃复合夹杂物;这种结构的夹杂物不易变形,在轧制过程中仍能保持球状或纺锤状,可使A类硫化物、B类氧化铝的评级均得到改善;钢中夹杂物更加弥散分布,钢中0～4μm~2小尺寸夹杂物比例上升,钢中夹杂物形貌的改善,更有利于提升钢材的性能。

Modification Effect of Magnesium Treatment on Inclusions in 0.45%C Steel

The types, sizes, distributions and morphological changes of inclusions in magnesium treated ( 0. 0006% Mg ) and calcium treated (0. 0010% Ca) 0.45% C steel are compared and analyzed by optical microscopy, scanning electron microscopy and in-situ electrolysis in non-aqueous solution. The results show that compared with the traditional calcium treatment process, after adding a certain amount of magnesium to 0.45% C steel, the Al₂O₃ in steel is transformed into fine and dispersed MgO ? Al₂ O₃ , and MnS takes MgO ? Al₂ O₃ as nucleation particles at the end of solidification to form MnS- MgO ? Al₂O₃ composite inclusions with soft outside and hard inside. The inclusions with this structure are not easy to deform ,and can still keep spherical or spindle shape during rolling, which can improve the ratings of A-type sulfide and B-type alumina; The inclusions in steel are more dispersed and distributed, the proportion of small-sized inclusions in steel with 0 ~ 4μm2 increases, and the morphology of inclusions in steel is improved which is more conducive to improving the properties of steel.