组合式电磁搅拌在铁素体不锈钢中的应用

Application of combined electromagnetic stirring in ferritic stainless steel

在铁素体不锈钢连铸过程中单独使用箱式电磁搅拌存在低倍组织中等轴晶比例控制不稳定以及搅拌强度带来的白亮带等问题。为改善铁素体不锈钢的低倍组织,开展了组合式电磁搅拌在铁素体不锈钢的应用。在工业试验条件下,分析了单独箱式、单独辊式以及箱式+辊式组合电磁搅拌等3种搅拌模式对410、430、441等铁素体不锈钢等轴晶比例和低倍质量的影响。结果表明,单独箱式和单独辊式均不能稳定控制铁素体不锈钢等轴晶比例。二冷上段单独施加箱式电磁搅拌或二冷下段单独施加辊式电磁搅拌,等轴晶比例均在50%以下。采用箱式+辊式组合电磁搅拌,较高拉速条件下(1号连铸机),对两段组合式电磁搅拌参数进行优化,箱式搅拌参数1210 A、2.7 Hz和辊式搅拌参数350 A、8 Hz,可以稳定地将等轴晶比例控制在60%以上,同时可以将二次柱状晶消除,得到较为理想的低倍组织;在较低拉速条件下(8号连铸机),采用箱式搅拌参数1200 A、3.5 Hz和辊式搅拌参数380 A、8 Hz组合,白亮带缺陷明显改善。

In the process of continuous casting of ferritic stainless steel,the use of box-type electromagnetic stirring alone has problems such as unstable control of the ratio of equiaxed grains in the macrostructure and white bright bands caused by the stirring intensity.In order to improve the macrostructure of ferritic stainless steel,the application of combined electromagnetic stirring in ferritic stainless steel was carried out.Under the condition of industrial test,the effects of three stirring modes,including single box type,single roller type and box and roller combined type on the equiaxed crystal ratio and macrostructure of the ferritic stainless steels of 410,430,441 were analyzed.The results show that neither the single box type nor the single roller type can stably control the equiaxed grain ratio of the ferritic stainless steel.The box-type electromagnetic stirring is applied to the upper section of the second cooling or the roller-type electromagnetic stirring is separately applied to the lower section of the second cooling,and the proportion of equiaxed crystals is below 50%.Adopt box type and roller type combined electromagnetic stirring,under the condition of higher casting speed(CCM1),the parameters of the combined electromagnetic stirring are optimized.The stirring parameter of the box type is 1210 A、2.7 Hz and the roller type is 350 A、8 Hz,which can stably control the ratio of equiaxed crystals to more than 60%,and at the same time can eliminate the secondary columnar crystals to obtain an ideal macrostructure.Under the condition of lower casting speed(CCM8),combined electromagnetic stirring parameters of the box stirring is 1200 A、3.5 Hz and roll stirring is 380 A、8 Hz,the white light band defect was significantly improved.