含硫齿轮钢SAE8620H热轧棒材夹杂物

 以EAF电炉—LF精炼炉—VD真空精炼炉—LF精炼炉—CC连铸工艺流程生产含硫齿轮钢SAE8620H热轧棒材，利用光学显微镜、扫描电镜和能谱仪分别对棒材横纵截面的边缘部位、1/2半径处和中心部位的夹杂物进行了检测，综合分析了夹杂物的尺寸、数量、分布以及形貌和成分。结果表明：含硫齿轮钢SAE8620H热轧棒材中的夹杂物主要有单独硫化锰和核心主要是Al2O3和MgO-Al2O3，外围是MnS或者（Ca、Mn）S的氧硫复合夹杂物；从边缘到中心，夹杂物总数递增，氧硫复合夹杂物比例递减；棒材横截面上夹杂物大部分小于2μm，长宽比小于3；棒材纵截面上夹杂物平均长度为11μm，边缘部位夹杂物平均长度较中心部位短3μm，纺锤状夹杂物的比例占30%。

Characteristics of Inclusions in High Sulfur Gear Steel SAE8620H Hot-Rolled Round Bar

The size, quantity, distribution, morphology and composition of inclusions in cross section and longitudinal section of high sulfur gear steel SAE8620H hot-rolled round bar produced with the EAF-LF-CC process were synthetically investigated by means of optical microscopy, scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the inclusions are mainly MnS and oxide-sulfide duplex inclusions formed by MnS or (Ca,Mn)S precipitating upon Al2O3 and MgO-Al2O3; the number of inclusions increases and the ratio of oxide-sulfide duplex inclusions decreases from surface to center of high sulfur gear steel SAE8620H hot-rolled round bar; the diameter and the aspect ratio of inclusions in cross section are mainly less than 2μm and 3 respectively;In the longitudinal section, the average length of inclusions is 11μm, the average length of inclusions at surface is less than that of center by 3μm and the ratio of spindle inclusions is only 30%.