ABSTRACT

This work continued to discuss the forms of Bi particles accompanying sulphide, and analysed the effect of Bi on tensile and machining properties in 1215MS free-cutting steel. The machining and tensile tests were carried out based on the as-cast steels. The effect of Bi on the size and hardness of sulphide was investigated. Results show that at 200 ppm Bi or more, the normalised frequency of the large-sized sulphide inclusions with area of above 50 μm² was maximum, 0.35. In Bi-containing steels, the forms of sulphide inclusions were summarized that: clustering, rodlike, long strip, spindle, ellipsoidal, and spherical shape. Most Bi particles adhering to sulphide inclusions mainly existed in steels. The average hardness of steel matrix and the inclusions in 240 ppm Bi steel were 103 and 116 kgf mm⁻¹, respectively. Bi added to steel increased the ductility and improved the surface finish of the machining steels.

摘要

这项工作继续讨论伴随硫化物的 Bi 颗粒的形式，并分析了 Bi 对 1215MS 易切削钢拉伸和加工性能的影响。基于铸态钢进行机械加工和拉伸试验。研究了铋对硫化物尺寸和硬度的影响。结果表明，在200 ppm Bi或更高时，面积大于50 μm ²的大尺寸硫化物夹杂物的归一化频率最大，为0.35。含铋钢中硫化物夹杂物的形态概括为：簇状、棒状、长条状、纺锤状、椭球状和球状。大多数附着在硫化物夹杂物上的铋颗粒主要存在于钢中。240 ppm Bi钢中钢基体和夹杂物的平​​均硬度分别为103和116 kgf mm^-1，分别。Bi添加到钢中提高了延展性并改善了加工钢的表面光洁度。