MgO-Al_2O_3-SiO_2复合夹杂物对430不锈钢凝固组织的影响  

Effect of MgO-Al_2O_3-SiO_2 Complex Inclusion on the Solidification Structure of 430 Stainless Steel

作　　者：田月美 陈兆平[2] 徐迎铁[2] 公茂涛[1,2] 疏达[1] 

机构地区：[1]上海交通大学金属基复合材料国家重点实验室,上海200240 [2]宝山钢铁股份有限公司研究院,上海201900

出　　处：《钢铁研究学报》2014年第6期61-66,共6页Journal of Iron and Steel Research

摘　　要：通过真空感应炉试验,研究不同Mg含量处理所获得的不同MgO-Al2O3-SiO2复合夹杂物对凝固组织的影响。试验结果表明,随着钢中Mg含量的增加,铸锭等轴晶率呈现先升高后下降的趋势,而等轴晶尺寸和柱状晶宽度呈现先降低后升高趋势,存在一个最佳的Mg的质量分数范围（5~13）×10-6,铸锭的等轴晶率在70%以上。夹杂物观测并结合热力学计算发现,随着钢中Mg含量的增加,MgO-Al2O3-SiO2复合夹杂物外层逐步析出MgO·Al2O3相;然而,Mg的质量分数高于13×10-6时,夹杂物外层开始析出2MgO·SiO2相。晶面错配度计算表明,MgO·Al2O3与δ-Fe的错配度为1.2%,2MgO·SiO2与δ-Fe的错配度为13%。可以判断,MgO·Al2O3相可促进等轴晶形成,抑制晶粒长大,2MgO·SiO2相则起不到促进形核作用。从而解释了铸锭等轴晶率、晶粒尺寸随Mg含量的变化规律。The composition of MgO-Al2O3-SiO2 complex inclusion,which formed by adding different quantity of Ni-Mg alloy to steel in MgO crucible induction melting furnace,had a huge effect on the solidification structure of 430 stainless steel.The experimental results show that with the increase of the content of magnesium in steel ingot,the ECR（equiaxed crystal ratio）can be increased at first and decreased subsequently,while the equiaxed crystal size and the width of the columnar should be first decreased then increased,and there exist an optimal range of magnesium content,（5-13）×10-6,in which the equiaxial crystal ingot is more than 70%.By connecting inclusion observation with thermodynamic calculation,when Mg content is less than 13×10-6,with the increase of[Mg],there will precipitate more MgO·Al2O3 phase around MgO-Al2O3-SiO2 complex inclusions;besides,when[Mg]is more than 13×10-6,there is 2 MgO·SiO2 phase around the inclusions.The planar disregistry calculation shows that the planar disregistry between the MgO·Al2O3 and δ-Fe is 1.2%,while the 2MgO·SiO2vsδ-Fe is 13%.It can be concluded that the MgO·Al2O3 around the MgO-Al2O3-SiO2 complex inclusion could promote the formation of equiaxed grains and refine the solidification structure of 430 stainless steel while the 2MgO·SiO2are unable to promote the nucleation,explaining the trend of the ECR and grain size of the ingot along with Mg content.

关 键 词：430不锈钢 等轴晶率 凝固组织 夹杂物 

分 类 号：TF764.1[冶金工程—钢铁冶金]